"old familiar friend, intimate companion," 1660s, chrony, Cambridge student slang, probably from Greek khronios "long-lasting," from khronos "time" (see chrono-), on the notion of "old friend" or "a contemporary."

1840, "friendship," from crony + -ism. Meaning "appointment of friends to important positions, regardless of ability" is originally American English, by 1952.

"one who lives at the same time as another," 1630s, originally cotemporary, from co- + temporary; modified by influence of contemporary (adj.). A native word for it was time-fellow (1570s), and earlier was contemporanie (early 15c.), from Latin contemporaneus, used as a noun. Also compare crony.