Origin and history of changeable

c. 1200, chaungen, "to alter, make different, change" (transitive); early 13c. as "to substitute one for another;" mid-13c. as "to make (something) other than what it was, cause to turn or pass from one state to another;" from late 13c. as "to become different, be altered" (intransitive), from Old French changier "to change, alter; exchange, switch," from Late Latin cambiare "to barter, exchange," extended form of Latin cambire "to exchange, barter."

This is held to be of Celtic origin, from PIE root *kemb- "to bend, crook" (with a sense evolution perhaps from "to turn" to "to change," to "to barter"); cognate with Old Irish camm "crooked, curved;" Middle Irish cimb "tribute," cimbid "prisoner;" see cant (n.2).

From c. 1300 as "undergo alteration, become different." In part an abbreviation of exchange. From late 14c. especially as "to give an equivalent for in smaller parts of the same kind" (money). The meaning "to take off clothes and put on other ones" is from late 15c. Related: Changed; changing. To change (one's) mind is from 1590s.

late 14c., entrechaungeable, "mutual, reciprocal," from inter- + changeable. Meaning "capable of being used in place of each other" is from 1560s. Related: Interchangeably.