archaic name for the Black Sea, from Latin Pontus Euxinus, from Greek Pontos Euxenios, literally "the hospitable sea," a euphemism for Pontos Axeinos, "the inhospitable sea." From eu- "good, well" (see eu-) + xenos "host; guest; stranger" (from PIE root *ghos-ti- "stranger, guest, host").

According to Room, The Old Persian name for the sea was akhshaena, literally "dark," probably in reference to the sudden, dangerous storms that make the sea perilous to sailors and darken its face (or perhaps in reference to the color of the water, from the sea being deep and relatively lifeless), and the Greeks took this untranslated as Pontos Axeinos, which was interpreted as the similar-sounding Greek word axenos "inhospitable." Thus the modern English name could reflect the Old Persian one.

Old English gæst, giest (Anglian gest) "an accidental guest, a chance comer, a stranger," from Proto-Germanic *gastiz (source also of Old Frisian jest, Dutch gast, German Gast, Gothic gasts "guest," originally "stranger"), from PIE root *ghos-ti- "stranger, guest, host" (source also of Latin hostis, in earlier use "a stranger," in classical use "an enemy"); the root sense, according to Watkins, probably is "someone with whom one has reciprocal duties of hospitality."

Spelling evolution influenced by Old Norse cognate gestr (the usual sound changes from the Old English word would have yielded Modern English *yest). Meaning "person entertained for pay" (at an inn, etc.) is from late 13c. Old English also had cuma "stranger, guest," literally "a comer." Phrase be my guest in the sense of "go right ahead" first recorded 1955.

1818, "rest house for travelers," especially the houses of refuge and shelter kept by monks in the passes of the Alps, from French hospice "hospital, almshouse" (Old French ospice "hospice, shelter," also "hospitality," 13c.), from Latin hospitium "hospitable reception, entertainment; hospitality, bonds of hospitality, relationship of guest and host;" also "place of entertainment, lodging, inn, guest-house," from hospes (genitive hospitis) "guest; host," also "a stranger, foreigner" (see host (n.1)).

Sense of "home for the aged and terminally ill " is from 1879; hospice movement first attested 1978.

"kind and cordial to strangers or guests," 1560s, from French hospitable, which is formed as if from a Medieval Latin hospitabilis, from the stem of Latin hospitari "be a guest," from hospes (genitive hospitis) "guest" (see host (n.1)). The Latin adjective was hospitalis, but this became a noun in Old French and entered English as hospital. Related: Hospitably.

mid-13c., "shelter for the needy," from Old French hospital, ospital "hostel, shelter, lodging" (Modern French hôpital), from Late Latin hospitale "guest-house, inn," noun use of neuter of Latin adjective hospitalis "of a guest or host" (as a noun, "a guest; the duties of hospitality"), from hospes (genitive hospitis) "guest; host;" see host (n.1).

The sense of "charitable institution to house and maintain the needy" in English is from early 15c.; the meaning "institution for sick or wounded people" is recorded by 1540s. The same word, contracted, is hostel and hotel. The sense shift in Latin from duties to buildings might have been via the common term cubiculum hospitalis "guest-chamber." The Latin adjective use continued in Old French, where ospital also could mean "hospitable" and ospitalite could mean "hospital."

late 14c., "act of being hospitable," from Old French ospitalité "hospitality; hospital," from Latin hospitalitem (nominative hospitalitas) "friendliness to guests," from hospes (genitive hospitis) "guest; host" (see host (n.1)).

former title of appointed Ottoman governors of Moldavia and Wallachia, 1680s, from Old Church Slavonic gospodi "lord, master," literally "lord of strangers," from gosti "guest, friend," from PIE *ghostis- "stranger" (from root *ghos-ti- "stranger, guest, host"); second element from PIE root *poti- "powerful; lord." Compare host (n.1).

"person who receives guests," especially for pay, late 13c., from Old French oste, hoste "guest, host, hostess, landlord" (12c., Modern French hôte), from Latin hospitem (nominative hospes) "guest, stranger, sojourner, visitor (hence also 'foreigner')," also "host; one bound by ties of hospitality."

This appears to be from PIE *ghos-pot-, a compound meaning "guest-master" (compare Old Church Slavonic gospodi "lord, master," literally "lord of strangers"), from the roots *ghos-ti- "stranger, guest, host" and *poti- "powerful; lord." The etymological notion is of someone "with whom one has reciprocal duties of hospitality" [Watkins]. The biological sense of "animal or plant having a parasite" is from 1857.

late 13c., from Old French ostage, hostage "kindness, hospitality; residence, dwelling; rent, tribute; compensation; guarantee, pledge, bail; person given as security or hostage" (11c., Modern French ôtage), which is of uncertain origin. Either from hoste "guest" (see host (n.1)) via notion of "a lodger held by a landlord as security" [Watkins, Barnhart]; or else from Late Latin obsidanus "condition of being held as security," from obses "hostage," from ob- "before" + base of sedere "to sit," with spelling influenced by Latin hostis. [OED, Century Dictionary]. Modern political/terrorism sense is from 1970.

early 13c., "inn, house of entertainment," from Old French ostel, hostel "house, home, dwelling; inn, lodgings, shelter" (11c., Modern French hôtel), from Medieval Latin hospitale "inn; large house" (see hospital). Obsolete after 16c., revived 1808, along with hostelry by Sir Walter Scott. Youth hostel is recorded by 1931.