mid-15c., commutacioun, "act of giving one thing for another," from Old French commutacion "change, transformation, exchange, barter" (13c., Modern French commutation), from Latin commutationem (nominative commutatio) "a change, alteration," noun of action from past participle stem of commutare "to change, alter entirely" (see commute (v.)).

From c. 1500 as "a passage from one state to another;" 1590s as "act of substituting one thing for another."

c. 1200, "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," a word 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 "to give an equivalent for in smaller parts of the same kind" (money). 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.

1530s, "alter, change over, transport," from Latin traducere "change over, convert," also "lead in parade, make a show of, dishonor, disgrace," originally "lead along or across, bring through, transfer" (source also of French traduire, Spanish traducir, Italian tradurre), from trans "across, beyond" (see trans-) + ducere "to lead" (from PIE root *deuk- "to lead"). Sense of "defame, slander" in English is from 1580s, from Latin traducere in the sense of "scorn or disgrace," a figurative use from the notion of "to lead along as a spectacle." Related: Traduced; traducing.

late 14c., resolven, "melt, dissolve, reduce to liquid; separate into component parts; alter, alter in form or nature by application of physical process," " intransitive sense from c. 1400; from Old French resolver or directly from Latin resolvere "to loosen, loose, unyoke, undo; explain; relax; set free; make void, dispel."

This is from re-, here perhaps intensive or meaning "back" (see re-), + solvere "to loosen, untie, release, explain," from PIE *se-lu-, from reflexive pronoun *s(w)e- (see idiom) + root *leu- "to loosen, divide, cut apart."

From the notion of "separate into components" comes the sense in optics (1785; see resolution). From the notion of "reduce by mental analysis into its basic forms" (late 14c.) comes the meaning "determine, decide upon" after analysis (1520s), hence "pass a resolution" (1580s); "decide, settle" a dispute, etc. (1610s). For sense evolution, compare resolute (adj.).

In Middle English also "vaporize a solid, condense a vapor into a liquid, etc.;" a mid-15c. document has Sche was resoluyd in-to terys where a later writer might have she dissolved in tears. Related: Resolved; resolving.

late 14c., reformacioun, "restoration, re-establishment;" early 15c., "improvement, alteration for the better," from Old French reformacion and directly from Latin reformationem (nominative reformatio), noun of action from past-participle stem of reformare "to form again, change, transform, alter," from re- "again" (see re-) + formare "to form" (see form (n.)).

With capital R-, in reference to the great 16c. European religious revolution, it is attested by 1540s, borrowed from Luther. The movement began as a bid to "reform" doctrines and practices of the Church of Rome.

1550s, "occurring or acting by turns, one after the other," present-participle adjective from alternate (v.). Electrical alternating current is recorded from 1839, an electrical current which flows alternately in opposite directions without interruption.