early 15c., moderacioun, "quality of being moderate or temperate; a lessening of rigor or severity," from Old French moderacion (14c.) "alteration, modification; mitigation, alleviation" and directly from Latin moderationem (nominative moderatio) "a controlling, guidance, government, regulation; moderation, temperateness, self-control," noun of action from past-participle stem of moderari "to regulate, mitigate, restrain, temper, set a measure, keep (something) within measure," from PIE root *med- "take appropriate measures." Meaning "act of moderating or restraining" is from 1520s.
late 14c., "self-restraint, moderation," especially with regard to desires and passions, "moderation in sexual intercourse, chastity, restraint of the sexual passions within lawful bounds," from Old French continence (14c.) and directly from Latin continentia "a holding back, repression," abstract noun from continent-, present-participle stem of continere "to hold back, check," also "hold together, enclose," from assimilated form of com "with, together" (see con-) + tenere "to hold" (from PIE root *ten- "to stretch").
In reference to the body's eliminatory functions, from 1915. Related: Continency.
late 14c., "moderate, temperate" (a sense now obsolete), past-participle adjective from measure (v.) in the sense of "exercise moderation." Meaning "uniform, regular, characterized by uniformity of movement or rhythm" is from c. 1400. That of "ascertained or determined by measuring" is from mid-15c. Meaning "deliberate, restrained" is from 1802.