effect: [14] Etymologically, an effect is that which is ‘accomplished’ or ‘done’. The word comes (probably via Old French effect) from effectus, the past participle of Latin efficere ‘perform, accomplish, complete’, or literally ‘work out’. This was a compound verb formed from the prefix ex- ‘out’ and facēre ‘make, do’ (source of English fact, factory, etc).
The English verbal use, ‘bring about’, is a 16th-century development based on the noun. (The similar affect also comes ultimately from Latin facēre, but with the prefix ad- ‘to’ rather than ex-.) Latin efficere is also the source of English efficacious [16] and efficient [14]. The feck- of feckless is an abbreviated version of effect. => efficacious, efficient, fact, factory, fashion, feckless
effect (n.)
mid-14c., "execution or completion (of an act)," from Old French efet (13c., Modern French effet) "result, execution, completion, ending," from Latin effectus "accomplishment, performance," from past participle stem of efficere "work out, accomplish," from ex- "out" (see ex-) + facere "to do" (see factitious). From French, borrowed into Dutch, German, Scandinavian.
From late 14c. as "power or capacity to produce an intended result; efficacy, effectiveness," and in astrology, "operation or action (of a heavenly body) on human affairs; influence." Also "that which follows from something else; a consequence, a result." From early 15c. as "intended result, purpose, object, intent." Also formerly with a sense of "reality, fact," hence in effect (late 14c.), originally "in fact, actually, really." Meaning "impression produced on the beholder" is from 1736. Sense in stage effect, sound effect, etc. first recorded 1881.
effect (v.)
"to produce as a result; to bring to a desired end," 1580s, from Latin effectus, past participle of efficere (see effect (n.)). Related: Effecting; effection.