greeting between persons meeting, 1848, early references are to the U.S. western frontier (where hello, the house was said to be the usual greeting upon approaching a habitation).
It is an alteration of hallo, itself an alteration of holla, hollo, a shout to attract attention, which seems to go back at least to late 14c. (compare Middle English verb halouen "to shout in the chase," hallouing). OED cites Old High German hala, hola, emphatic imperative of halon, holon "to fetch," "used especially in hailing a ferryman." Fowler in the 1920s listed halloo, hallo, halloa, halloo, hello, hillo, hilloa, holla, holler, hollo, holloa, hollow, hullo, and writes, "The multiplicity of forms is bewildering ...."
Its rise to popularity as a greeting (1880s) coincides with the spread of the telephone, where it won out as the word said in answering, over Alexander Graham Bell's suggestion, ahoy. Central telephone exchange operators were known as hello-girls (1889).
Hello, formerly an Americanism, is now nearly as common as hullo in Britain (Say who you are; do not just say 'hello' is the warning given in our telephone directories) and the Englishman cannot be expected to give up the right to say hello if he likes it better than his native hullo. [H.W. Fowler, "A Dictionary of Modern English Usage," 1926]
"ogre, devouring monster," 1590s, perhaps a reborrowing of the same word that became Old English orcþyrs, orcneas (plural), which is perhaps from a Romanic source akin to ogre, and ultimately from Latin Orcus "Hell," a word of unknown origin. Also see Orca. Revived by J.R.R. Tolkien (1892-1973), who might have got it from Beowulf, as the name of a brutal race in Middle Earth.
But Orcs and Trolls spoke as they would, without love of words or things; and their language was actually more degraded and filthy than I have shown it. ["Return of the King," 1955]
late 14c. in Latin form abyssus, "depths of the earth or sea; primordial chaos;" early 14c. as abime "depths of the earth or sea; bottomless pit, Hell" (from Old French; see abysm). Both are from Late Latin abyssus "bottomless pit," from Greek abyssos (limne) "bottomless (pool)," from abyssos "bottomless, unfathomed," hence, generally, "enormous, unfathomable," also as a noun, he abyssos "the great depth, the underworld, the bottomless pit." This is a compound of a- "without" (see a- (3)) + byssos "bottom," a word of uncertain origin possibly related to bathos "depth" [Liddell & Scott]. Watkins suggests a connection with the root of bottom (n.); Beekes suggests it is pre-Greek.
The current form in English is a 16c. partial re-Latinization. Greek abyssos was used in Septuagint to translate Hebrew tehom "original chaos" and was used in the New Testament for "Hell." OED notes, "the word has had five variants, abime, abysm, abysmus, abyssus, abyss; of which abyss remains as the ordinary form, and abysm as archaic or poetic." In reference to a seemingly bottomless gulf from 1630s. Old English glossed Latin abyssum with deagenesse, which is related to deagol "secret, hidden; dark, obscure."
1570s, "godless person, one who denies the existence of a supreme, intelligent being to whom moral obligation is due," from French athéiste (16c.), from Greek atheos "without god, denying the gods; abandoned of the gods; godless, ungodly," from a- "without" (see a- (3)) + theos "a god" (from PIE root *dhes-, forming words for religious concepts).
The existence of a world without God seems to me less absurd than the presence of a God, existing in all his perfection, creating an imperfect man in order to make him run the risk of Hell. [Armand Salacrou, "Certitudes et incertitudes," 1943]
mid-14c., "condition of damnation, spiritual ruin, state of the souls of the wicked in Hell," a special theological sense; the general sense of "utter destruction, entire ruin, great harm, death, fact of being lost or destroyed," is by late 14c.; from Old French perdicion "loss, calamity, perdition" of souls (11c.) and directly from Late Latin perditionem (nominative perditio) "ruin, destruction," noun of action from past-participle stem of Latin perdere "do away with, destroy; lose, throw away, squander," from per- "through" (here perhaps with intensive or completive force, "to destruction") + dare "to give" (from PIE root *do- "to give"). The theological sense gradually extinguished the general use of the word.