late Old English hrung "rod, cross-bar; stout, rounded stick," from Proto-Germanic *khrungo (source also of Middle Low German runge, Old High German runga "stake, stud, stave," German Runge "stake, stud, stave," Middle Dutch ronghe, Dutch rong "rung," Gothic hrugga "staff"), a word of unknown origin with no connections outside Germanic if as is supposed the Celtic words are from English.

The sense in English narrowed to mean usually "round or stave of a ladder" (attested from late 13c.), but usage of cognate words remains more general in other Germanic languages.

This [rungs] has generally been considered as a mere corruption of rounds; and people of education use only this latter word. [John Pickering, "A Vocabulary or Collection of Words and Phrases which have been Supposed to be Peculiar to the United States of America," Boston, 1816]

1727, "resemblance of sounds between words other than rhyme," from French assonance, from assonant, from Latin assonantem (nominative assonans), present participle of assonare/adsonare "to resound, respond," from ad "to" (see ad-) + sonare "to sound" (from PIE root *swen- "to sound").

The more specific sense in prosody of "rhyming or correspondence of accented vowels but not consonants" is from 1823. In 20c. the sense tended to merge with consonance in the notion of slant rhyme, off rhyme, but properly there is a distinction.

Assonance is the relationship between words with different consonants immediately preceding and following the last accented vowels, which vowels have identical sounds (hit/will, disturb/bird, absolute/unglued). Consonance is the relationship between words whose final accented vowel sounds are different but with the same consonant frame (truck/trick, billion/bullion, impelling/compiling, trance/trounce). [Miller Williams, "Patterns of Poetry"]

umbelliferous European plant long cultivated as food, 1660s, sellery, from French céleri (17c., originally sceleri d'Italie), said by French sources to be from Italian (Lombard dialect) seleri (singular selero), from Late Latin selinon, from Greek selinon "parsley" (in Medieval Greek "celery"), a word of uncertain origin. The c- spelling, attested by 1719 in English, is from French. Middle English words for "wild celery" were acheand selinum.

[O]ne day, in a weak and hungry moment, my roommate and I succumbed to a bit of larceny. A greengrocer's truck had parked down the street and was left unattended. We grabbed the first crate we could off the back. It turned out to be celery. For two days we ate nothing but celery and used up more calories chewing than we realized in energy. "Damn it," I said to my roommate, "What're we going to do? We can't starve." "That's funny," he replied. "I thought we could." [Chuck Jones, "Chuck Amuck," 1989]

1580s, in the rhetorical sense ("a chain of reasoning in graduating steps from weaker to stronger"), from Late Latin climax (genitive climacis), from Greek klimax "propositions rising in effectiveness," literally "ladder," from suffixed form of PIE root *klei- "to lean."

Originally in rhetoric an arrangement of successive clauses so that the last important word of one is repeated as the first important word of the next, as in Romans v.3-5: "... but we glory in tribulations also: knowing that tribulation worketh patience; and patience, experience; and experience, hope: And hope maketh not ashamed ...." Compare anadiplosis. From the rhetorical meaning, the word evolved through "series of steps by which a goal is achieved," to "escalating steps," to (1789) "high point of intensity or development," a usage credited by the OED to "popular ignorance."

The meaning "sexual orgasm" is recorded by 1880 (also in terms such as climax of orgasm), and is said to have been promoted from c. 1900 by birth-control pioneer Marie Stopes (1880-1958) and others as a more accessible word than orgasm (n.).

1510s, "degree of measurement," from French grade "grade, degree" (16c.), from Latin gradus "a step, a pace, gait; a step climbed (on a ladder or stair);" figuratively "a step toward something, a degree of something rising by stages," from gradi (past participle gressus) "to walk, step, go," from PIE root *ghredh- "to walk, go." It replaced Middle English gree "a step, degree in a series," from Old French grei "step," from Latin gradus.

Meaning "inclination of a road or railroad" is from 1811. Meaning "class of things having the same quality or value" is from 1807; meaning "division of a school curriculum equivalent to one year" is from 1835; that of "letter-mark indicating assessment of a student's work" is from 1886 (earlier used of numerical grades). Grade A "top quality, fit for human consumption" (originally of milk) is from a U.S. system instituted in 1912. To figuratively make the grade "be successful" is from 1912; early examples do not make clear whether the literal grade in mind was one of elevation, quality, or scholarship.

1620s, "a critical stage in human life, a period supposed to be especially liable to remarkable change with regard to health, life or fortune," from Latin climactericus, from Greek klimaktērikos "of a critical period," from klimaktēr "rung of a ladder," figuratively "critical point of a man's life" (see climax (n.)).

By some, held to be the years that are multiples of 7 (14, 21, 28, etc.), by others only the 3rd, 5th, 7th, and ninth periods of 7 years (21, 35, 49, etc.), to which some added the 81st year. By still others it was regarded as the years that were multiples of 9. The greator grand climacteric,supposed to be especially remarkable, was the 63rd year (7x9) or the 81st (9x9).

In 19c. medicine it often especially meant "menopause." Climacteric was used earlier in English as an adjective, "pertaining to a critical period or crisis" (c. 1600; climacterical in this sense is from 1580s).  

mid-13c., "story of a building;" early 14c., "raised platform used for public display" (also "the platform beneath the gallows"), from Old French estage "building, dwelling place; stage for performance; phase, stage, rest in a journey" (12c., Modern French étage "story of a house, stage, floor, loft"), from Vulgar Latin *staticum "a place for standing," from Latin statum, past participle of stare "to stand," from PIE root *sta- "to stand, make or be firm." Meaning "platform for presentation of a play" is attested from late 14c.; generalized for "profession of an actor" from 1580s.

Sense of "period of development or time in life" first recorded early 14c., probably from Middle English sense of "degree or step on the 'ladder' of virtue, 'wheel' of fortune, etc.," in parable illustrations and morality plays. Meaning "a step in sequence, a stage of a journey" is late 14c. Meaning "level of water in a river, etc." is from 1814, American English.

Stage-name is from 1727. Stage-mother (n.) in the overbearing mother-of-an-actress sense is from 1915. Stage-door is from 1761, hence Stage-Door Johnny "young man who frequents stage doors seeking the company of actresses, chorus girls, etc." (1907). Stage whisper, such as used by an actor on stage to be heard by the audience, first attested 1865. Stage-manage (v.) is from 1871.

"pointed stick or post; stick of wood sharpened at one end for driving into the ground, used as part of a fence, as a boundary-mark, as a post to tether an animal to, or as a support for something (a vine, a tent, etc.)," Old English staca "pin, stake," from Proto-Germanic *stakon (source also of Old Norse stiaki "a stake, pole, candlestick,"Old Frisian stake, Middle Dutch stake, Dutch staak "a stake, post," Middle Low German stake "a stake, post, pillory, prison"), from PIE root *steg- (1) "pole, stick." The Germanic word was borrowed in Romanic (Spanish and Portuguese estaca "a stake," Old French estaque, estache, Italian stacca "a hook"), and was borrowed back as attach.

Meaning "post to which a person condemned to death by burning is bound" is from c. 1200, also "post to which a bear to be baited is tied" (late 14c.). Meaning "vertical bar fixed in a socket or in staples on the edge of the bed of a platform railway-car or of a vehicle to secure the load from rolling off, or, when a loose substance, as gravel, etc., is carried, to hold in place boards which retain the load," is by 1875; hence stake-body as a type of truck (1903).

Pull up stakes was used c. 1400 as "abandon a position" (the allusion is to pulling up the stakes of a tent); the modern American English figurative expression in the sense of "move one's habitation" is by 1703.

plural of man (n.). In common with German Männer, etc., it shows effects of i-mutation. Used as an indefinite pronoun ("one, people, they") from late Old English. Men's liberation first attested 1970. Men's room "a lavatory for men" is by 1908, American English. Earlier it had a more general sense:

men's room, n. "One end of this [cook and dining] room is partitioned off for a men's room, where the crew sit evenings, smoking, reading, singing, grinding their axes, telling stories, etc., before climbing the ladder to their night's rest in the bunk room ... For many years women have been employed in [logging] camps as cooks, hence the name men's room, for the crew are not allowed in the cook room except at meal time." [quoted in "Some Lumber and Other Words," in Dialect Notes, vol. II, part VI, 1904]

Menswear (also men's wear) "clothes for men" is by 1906. To separate the men from the boys in a figurative sense "distinguish the manly, mature, capable, etc. in a group from the rest" is from 1943; earliest uses tend to credit it to U.S. aviators in World War II.

One of the most expressive G.I. terms to come out of the late strife was "that's where they separate the men from the boys" — so stated by American aviators leaning from their cockpits to observe a beach-landing under fire on some Pacific island far below. ["Arts Magazine," 1947]

"bent or angled piece of metal or other substance used to catch or hold something," Old English hoc "hook, angle," perhaps related to Old English haca "bolt," from Proto-Germanic *hokaz/*hakan (source also of Old Frisian hok, Middle Dutch hoek "a hook;" Dutch haak "a hook, angle, corner, cape," German Haken "hook"), from PIE root *keg- "hook, tooth." For spelling, see hood (n.1).

Also the name of a fireman's tool for tearing into buildings, hence hook-and-ladder (1821). Meaning "holder for a telephone receiver" is from 1885 and continued in use after the mechanism evolved. Boxing sense of "short, swinging blow with the elbow bent" is from 1898. Figurative sense "that which catches, a snare, trap" is from early 15c. Meaning "projecting point of land" is from 1670s; in U.S. use probably reinforced by the Dutch word.

This name is given in New York to several angular points in the North and East rivers; as Corlear's Hook, Sandy Hook, Powles's Hook. [Bartlett, "Dictionary of Americanisms," 1848]

Off the hooks meant "disordered" (16c.), "unhinged" (1610s) and "dead" (1840). By hook or by crook (late 14c.) probably alludes to tools of professional thieves. Hook, line, and sinker "completely" is 1838, a metaphor from angling. Hook-nose (n.) is from 1680s; hook-nosed (adj.) from 1510s. Hook-and-eye as a method of garment fastening is from 1620s.

Hook and eye, a metallic fastening for garments, consisting of a hook, commonly of flattened wire bent to the required shape, and an eye, usually of the same material, into which the hook fits. Under the name of crochet and loop, this form of fastening was in use as early as the fourteenth century. [Century Dictionary]