default n.

active word-forming element in English and in many verbs inherited from French and Latin, from Latin de "down, down from, from, off; concerning" (see de), also used as a prefix in Latin, usually meaning "down, off, away, from among, down from," but also "down to the bottom, totally" hence "completely" (intensive or completive), which is its sense in many English words.

As a Latin prefix it also had the function of undoing or reversing a verb's action, and hence it came to be used as a pure privative — "not, do the opposite of, undo" — which is its primary function as a living prefix in English, as in defrost (1895), defuse (1943), de-escalate (1964), etc. In some cases, a reduced form of dis-.

c. 1200, "be unsuccessful in accomplishing a purpose;" also "cease to exist or to function, come to an end;" early 13c. as "fail in expectation or performance," from Old French falir "be lacking, miss, not succeed; run out, come to an end; err, make a mistake; be dying; let down, disappoint" (11c., Modern French faillir), from Vulgar Latin *fallire, from Latin fallere "to trip, cause to fall;" figuratively "to deceive, trick, dupe, cheat, elude; fail, be lacking or defective." De Vaan traces this to a PIE root meaning "to stumble" (source also of Sanskrit skhalate "to stumble, fail;" Middle Persian škarwidan "to stumble, stagger;" Greek sphallein "to bring or throw down," sphallomai "to fall;" Armenian sxalem "to stumble, fail"). If so, the Latin sense is a metaphorical shift from "stumble" to "deceive." Related: Failed; failing.

Replaced Old English abreoðan. From c. 1200 as "be unsuccessful in accomplishing a purpose;" also "cease to exist or to function, come to an end;" early 13c. as "fail in expectation or performance."

From mid-13c. of food, goods, etc., "to run short in supply, be used up;" from c. 1300 of crops, seeds, land. From c. 1300 of strength, spirits, courage, etc., "suffer loss of vigor; grow feeble;" from mid-14c. of persons. From late 14c. of material objects, "break down, go to pieces."

"one who fails to perform some duty or obligation," 1650s, agent noun from default (v.).