late 14c., duete, "obligatory service, that which ought to be done," also "the force of that which is morally right," from Anglo-French duete, from Old French deu "due, owed," hence "proper, just" (on the notion of "that which one is bound by natural, moral, or legal obligation to do or perform"); from Vulgar Latin *debutus, from Latin debitus, past participle of debere "to owe," originally, "keep something away from someone," from de- "away" (see de-) + habere "to have" (from PIE root *ghabh- "to give or receive"). Related: Duties.
Military sense of "a requisite service" is by 1580s. The sense of "tax or fee on imports, exports, etc." is from late 14c.; hence duty-free (adv.) "free from tax or duty" (1680s), and, as a noun, "duty-free article" (1958), "duty-free shop" (by 1980).
It forms all or part of: able; avoirdupois; binnacle; cohabit; cohabitation; debenture; debit; debt; dishabille; due; duty; endeavor; exhibit; exhibition; forgive; gavel; gift; give; habeas corpus; habiliment; habit; habitable; habitant; habitat; habitation; habitual; habituate; habituation; habitude; habitue; inhabit; inhibit; inhibition; malady; prebend; prohibit; prohibition; provender.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit gabhasti- "hand, forearm;" Latin habere "to have, hold, possess," habitus "condition, demeanor, appearance, dress;" Old Irish gaibim "I take, hold, I have," gabal "act of taking;" Lithuanian gabana "armful," gabenti "to remove;" Gothic gabei "riches;" Old English giefan, Old Norse gefa "to give."
"one who fails to perform some duty or obligation," 1650s, agent noun from default (v.).