porphyrite (n.)
1796 as a modern mineral name, from porphyry + -ite (2). Related: Porphyritic.
porphyry (n.)
type of ornamental stone, late 14c., porfurie, from Old French porfire, from Italian porfiro and in some cases directly from Latin porphyrites, a purple semi-precious stone quarried near the Red Sea in Egypt, from Greek porphyrites (lithos) "the purple (stone)," from porphyra (n.) "purple, purple dye" (see purple). Spelling Latinized mid-15c. Now used generally for a type of igneous rock without regard to color. Porphyrios was an ancient proper name.
porpoise (n.)
early 14c., porpas, from Old French porpais (12c.) "porpoise," literally "pork fish," from porc "pork" (see pork (n.)) + peis "fish," from Latin piscis "fish" (see fish (n.)).

The Old French word probably is a loan-translation of a Germanic word meaning literally "sea-hog, mere-swine," such as Old Norse mar-svin, Old High German meri-swin, Middle Dutch mereswijn "porpoise" (the last of which also was borrowed directly into French and became Modern French marsouin).

Classical Latin had a similar name, porculus marinus (in Pliny), and the notion behind the name likely is a fancied resemblance of the snout to that of a pig.
porridge (n.)
1530s, porage "soup of meat and vegetables," alteration of pottage, perhaps from influence of Middle English porray, porreie "leek broth," from Old French poree "leek soup," from Vulgar Latin *porrata, from Latin porrum "leek." Spelling with -idge attested from c.1600. Association with oatmeal is 1640s, first in Scottish.
porringer (n.)
late 15c., alteration of potynger, potager "small dish for stew," from Middle English potage (see pottage) by the same course of changes that produced porridge; and with intrusive -n- by 1530s (compare passenger).
port (n.1)
"harbor," Old English port "harbor, haven," reinforced by Old French port "harbor, port; mountain pass;" Old English and Old French words both from Latin portus "port, harbor," originally "entrance, passage," figuratively "place of refuge, assylum," from PIE *prtu- "a going, a passage," from root *per- (2) "to lead, pass over" (cognates: Sanskrit parayati "carries over;" Greek poros "journey, passage, way," peirein "to pierce, run through;" Latin porta "gate, door," portare "passage," peritus "experienced;" Avestan peretush "passage, ford, bridge;" Armenian hordan "go forward;" Welsh rhyd "ford;" Old Church Slavonic pariti "to fly;" Old English faran "to go, journey," Old Norse fjörðr "inlet, estuary").

Meaning "left side of a ship" (looking forward from the stern) is attested from 1540s, from notion of "the side facing the harbor" (when a ship is docked). It replaced larboard in common usage to avoid confusion with starboard; officially so by Admiralty order of 1844 and U.S. Navy Department notice of 1846. Figurative sense "place of refuge" is attested from early 15c.; phrase any port in a storm first recorded 1749. A port of call (1810) is one paid a scheduled visit by a ship.
port (n.2)
"gateway," Old English port "portal, door, gate, entrance," from Old French porte "gate, entrance," from Latin porta "city gate, gate; door, entrance," from PIE root *per- (see port (n.1)). Specific meaning "porthole, opening in the side of a ship" is attested from c.1300.
port (n.3)
"bearing, mien," c.1300, from Old French port, from porter "to carry," from Latin portare (see port (n.1)).
port (n.4)
type of sweet dark-red wine, 1690s, shortened from Oporto, city in northwest Portugal from which the wine originally was shipped to England; from O Porto "the port;" (see port (n.1)).
port (v.)
"to carry," from Middle French porter, from Latin portare "to carry" (see port (n.1)). Related: Ported; porting.
port-wine (n.)
1700, from port (n.4) + wine (n.).
portable (adj.)
early 15c., from French portable "that can be carried," from Late Latin portabilis "that can be carried," from Latin portare "to carry" (see port (n.1)). Related: Portability.
portage (n.)
early 15c., "action of carrying," said to be from Old French portage, Medieval Latin portaticum, though the meaning of these was "tax paid on entering a town," from Latin portare "to carry" (see port (n.1)). Sense of "carrying of boats from one navigable water to another" is from 1690s, reinforced in Canadian French.
portal (n.)
late 14c., "gate, gateway," from Old French portal "gate" (Modern French portail) and directly from Medieval Latin portale "city gate, porch," from neuter of portalis (adj.) "of a gate," from Latin porta "gate" (see port (n.1)).
portcullis (n.)
also port-cullis, c.1300, from Old French porte coleice "sliding gate" (c.1200, Modern French porte à coulisse), from porte "gate" (see port (n.2)) + coleice "sliding, flowing," fem. of coleis, from Latin colatus, past participle of colare "to filter, strain" (see colander).
Porte (n.)
"Ottoman court at Constantinople," c.1600, from French, in full, la Sublime Porte, literally "the high gate," translation of Arabic al-Bab al-'Ali, "lofty gate," official name of the central office of the Ottoman government (compare Vatican for "the Papacy," White House for "the United States"). Compare also mikado. Supposedly a reference to the ancient custom of holding royal audience in the doorway of a king's palace or tent.
porte-cochere (n.)
gateway for carriages, 1690s, from French porte-cochère, from porte "gate" (see port (n.2)) + cochère, fem. adjective from coche "coach" (see coach (n.)).
portend (v.)
early 15c., from Latin portendere "foretell, reveal; point out, indicate," originally "to stretch forward," from por- (variant of pro-; see pro-) "forth, forward" + tendere "to stretch, extend" (see tenet). Related: Portended; portending.
portent (n.)
1560s, from Middle French portente, from Latin portentum "a sign, token, omen; monster, monstrosity," noun use of neuter of portentus, past participle of portendre (see portend).
portentous (adj.)
1540s, from Latin portentosus "monstrous, marvelous, threatening," from portentem "portent" (see portend). Related: Portentously.
porter (n.1)
"person who carries," late 14c. (mid-13c. as a surname), from Anglo-French portour, Old French porteor "porter, bearer; reporter" (12c.), from Late Latin portatorem (nominative portator) "carrier, one who carries," from past participle stem of Latin portare "to carry" (see port (n.1)).
porter (n.2)
"doorkeeper, janitor," mid-13c. (late 12c. as a surname), from Anglo-French portour, Old French portier "gatekeeper" (12c.), from Late Latin portarius "gatekeeper," from Latin porta "gate" (see port (n.2)).
porter (n.3)
type of dark beer, 1734, short for porter's ale (1721), from porter (n.1), because the beer was made for or preferred by porters and other laborers, being cheap and strong.
porterhouse (n.)
also porter-house, "restaurant or chophouse where porter is served," 1754, from porter (n.3) + house (n.). Porterhouse steak (1841) is said to be from a particular establishment in New York City.
portfolio (n.)
1722, porto folio; 1719 as port folio, from Italian portafoglio "a case for carrying loose papers," from porta, imperative of portare "to carry" (see port (n.1)) + foglio "sheet, leaf," from Latin folium (see folio). Meaning "official documents of a state department" is from 1835. A minister without portfolio is one not in charge of a particular department. Meaning "collection of securities held" is from 1930; portfolio investment is from 1955.
porthole (n.)
also port-hole, 1590s, from port (n.2) + hole (n.).
portico (n.)
c.1600, from Italian portico, from Latin porticus "colonnade, arcade, covered walk, porch," from porta "gate" (see port (n.1)). Especially of the Painted Porch in Athens.
portiere (n.)
door curtain, 1843, from French portière, from Medieval Latin portaria, fem. singular of Latin portarius "belonging to a door or gate" (see porter (n.2)).
portion (n.)
early 14c., "allotted part, share," from Old French porcion "part, portion" (12c., Modern French portion) and directly from Latin portionem (nominative portio) "share, part," accusative of the noun in the phrase pro portione "according to the relation (of parts to each other)" (see proportion). From late 14c. in general sense of "section into which something is divided."
portion (v.)
"to divide in portions," early 14c., from Old French porcioner "share out, divide in portions," from porcion (see portion (n.)). Related: Portioned; portioning.
Portland
in Portland cement, 1720, named by its inventor, English mason Joseph Aspdin, from resemblance of the color to the stone of Portland peninsula on the coast of Dorsetshire. The place name is literally "land surrounding a harbor," Old English Portlanda. Portland, Maine, U.S.A., took its name 1786, for the place in England. Portland, Oregon, was said to have been named for the city in Maine, which won the honor by a coin toss over Boston.
portly (adj.)
early 15c., "stately, dignified," from port (n.3) "bearing, carriage" + -ly (1). Meaning "stout" is first recorded 1590s.
portmanteau (n.)
1580s, "traveling case or bag for clothes and other necessaries," from Middle French portemanteau "traveling bag," originally "court official who carried a prince's mantle" (1540s), from porte, imperative of porter "to carry" (see porter (n.1)) + manteau "cloak" (see mantle (n.)).

Portmanteau word "word blending the sound of two different words" (1882), coined by "Lewis Carroll" (Charles L. Dodgson, 1832-1898) for the sort of words he invented for "Jabberwocky," on notion of "two meanings packed up into one word." As a noun in this sense from 1872.
portobello
type of mushroom, by 1986, no agreed-upon theory accounts for the name, which seems to be a marketing coinage. London's Portobello Road (one suggested source of the mushroom name) originally was the lane to Porto Bello House, named for the Panamanian place captured by the British under Vernon in 1739.
portrait (n.)
1560s, "a figure, drawn or painted," a back formation from portraiture or directly from Middle French portrait, from Old French portret (13c.), noun use of past participle of portraire "to paint, depict" (see portray). Especially of the head and face of a person.
portraiture (n.)
mid-14c., from Old French portraiture "portrait, image, portrayal, resemblance" (12c.), from portrait (see portrait).
portray (v.)
mid-13c., "to draw, paint" (something), from Anglo-French purtraire, Old French portraire "to draw, to paint, portray" (12c.), literally "trace, draw forth," from por- "forth" (from Latin pro-; see pro-) + traire "trace, draw," from Latin trahere "to drag, draw" (see tract (n.1)). Meaning "depict in words, describe" is from late 14c. Related: Portrayed; portraying.
portrayal (n.)
1834, from portray + -al (2). The idea formerly was expressed by portray (n.), 1610s.
portsider (n.)
"left-handed person," 1913, American English baseball slang, from port (n.1) in the nautical sense + side (n.).
Portugal
late 14c., Portyngale, from Medieval Latin Portus Cale (Roman name of modern Oporto), "the port of Gaya." Alfonso, Count of Portucale, became the first king of Portugal.
Portuguese (n.)
1610s, the language, or a resident, of Portugal; 1660s as an adjective, from Portuguese Portuguez (see Portugal + -ese). The ending was vulgarly mistaken for a plural in English, and false singular Portugee (1830) was formed (compare Chinee from Chinese). For Portuguese man-of-war, see man-of-war.
posable (adj.)
1972 of questions; 1975 of action figures; from pose (v.1 and 2) + -able.
posada (n.)
"inn," 1763, from Spanish posada "home, lodging," from posar "to repose, rest, lodge," from Latin pausare (see pause (v.)).
pose (v.1)
late 14c., "suggest, propose, suppose, assume," from Old French poser "put, place, propose," a term in debating, from Late Latin pausare "to halt, rest, pause" (source also of Italian posare, Spanish posar; see pause (v.)). The Old French verb (in common with cognates in Spanish, Italian, Portuguese) acquired the sense of Latin ponere "to put, place," by confusion of the similar stems. Meaning "put in a certain position" is from early 15c. Sense of "assume a certain attitude" is from 1840; the transitive sense (as an artist's model, etc.) is from 1859. Related: Posed; posing.
pose (v.2)
"to puzzle, confuse, perplex," 1590s, earlier "question, interrogate" (1520s), probably from Middle French poser "suppose, assume," from Old French poser "to put, place, set" (see pose (v.1)). Also in some cases a shortening of English appose "examine closely," and oppose. Related: Posed; posing.
pose (n.)
"act of posing the body," 1818, from pose (v.1), in a sense developed in the French cognate. Figuratively from 1884.
Poseidon (n.)
Greek god of the sea and earthquakes, Greek Poseidon (Doric Poteidan), of uncertain origin.
poser (n.)
"one who practices an affected attitude," 1881, agent noun from pose (v.1); revived in teen-ager slang by 1983. Meaning "question that puzzles" is from 1793 from pose (v.2); earlier it meant "one who asks testing questions" (1580s).
poseur (n.)
"one who practices affected attitudes," 1866, from French poseur, from verb poser "affect an attitude or pose," from Old French poser "to put, place, set" (see pose (v.1)). The word is English poser in French garb, and thus could itself be considered an affectation.
posh (adj.)
by 1914 (1903 as push), of uncertain origin; no evidence for the common derivation from an acronym of port outward, starboard home, supposedly the shipboard accommodations of wealthy British traveling to India on the P & O Lines (to keep their cabins out of the sun); as per OED, see objections outlined in G. Chowdharay-Best, "Mariner's Mirror," Jan. 1971; also see here. More likely from slang posh "a dandy" (1890), from thieves' slang meaning "money" (1830), originally "coin of small value, halfpenny," possibly from Romany posh "half" [Barnhart].
The cavalryman, far more than the infantryman, makes a point of wearing "posh" clothing on every possible occasion -- "posh" being a term used to designate superior clothing, or articles of attire other than those issued by and strictly conforming to the regulations. [E. Charles Vivian, "The British Army From Within," London, 1914]