late 15c., "a covenant or agreement," from French convenance "convention, agreement, convenience," from convenant, present participle of convenir "to come together; join, fit, suit" (see convene). Meaning "conventional propriety" is from 1847.
c. 1600, "action of adapting (something to something else)," from French adaptation, from Late Latin adaptationem (nominative adaptatio), noun of action from past-participle stem of adaptare "to adjust," from ad "to" (see ad-) + aptare "to join," from aptus "fitted" (see apt).
The meaning "condition of being adapted, state of being fitted to circumstances or relations" is from 1670s. The sense of "modification of a thing to suit new conditions" is from 1790. The biological sense of "variations in a living thing to suit changed conditions" is by 1859, in Darwin's writings.
toasted cheese and bread, 1706, from French ramequin (late 17c.), said to be from a Germanic source (compare Middle Low German rom "cream"), from Proto-Germanic *rau(g)ma-, which is of uncertain origin.
see jail (n.), you tea-sodden football hooligan. Formerly in official use in Britain, and thus sometimes regarded in U.S. as a characteristic British spelling (though George Washington used it); by the time of OED 2nd edition (1980s) both spellings were considered correct there; the g- spelling is said to have been dominant longest in Australia.
[T]he very anomalous pronunciation of g soft before other vowels than e, i, & y ... is a strong argument for writing jail [Fowler]