"to station at a place," 1680s, from post (n.2) "place when on duty." Related: Posted; posting.

"science of moral duty, ethics," 1817, from Greek deont-, combining form of deon "that which is binding, duty" (neuter present participle of dei "is binding") + -ology. Said to have been coined by Bentham, but it is used in a wider sense than he intended it. Related: Deontological.

"dead, deceased, extinct," 1590s, from Old French defunct (14c., Modern French defunt) or directly from Latin defunctus "dead," literally "off-duty," past-participle adjective from defungi "to discharge, finish," from de- "off, completely" (see de-) + fungi "perform or discharge duty" (see function (n.)).

early 14c., "a loud cry, an outcry," also "a summons, an invitation," from call (v.). From 1580s as "a summons" (by bugle, drum, etc.) to military men to perform some duty; from 1680s as "the cry or note of a bird." Sense of "a short formal visit" is from 1862; meaning "a communication by telephone" is from 1878. From 1670s as "requirement, duty, right," hence, colloquially, "occasion, cause."

"sacrifice of what commonly constitutes the happiness of life for the sake of duty or higher motive," 1650s; see self + sacrifice (n.). Adjective self-sacrificed attested from 1711. Related: self-sacrificing.

Self-sacrifice goes beyond self-denial in necessarily including the idea of surrender, as of comfort, inclination, time, health, while being also presumably in the line of a real duty. [Century Dictionary]

"failure or omission of duty or obligation," 1630s, from Late Latin delinquentia "fault, crime, delinquency," from Latin delinquentem (see delinquent).

"seduced or corrupted from duty or virtue, vitiated in morals or purity of character," 1590s, past-participle adjective from debauch (v.). Related: Debauchedness.