self-denial (n.)

word forming element indicating "oneself," also "automatic," from Old English use of self (pron.) in compounds, such as selfbana "suicide," selflice "self-love, pride, vanity, egotism," selfwill "free will." Middle English had self-witte "one's own knowledge and intelligence" (early 15c.).

OED counts 13 such compounds in Old English. Middle English Compendium lists four, counting the self-will group as a whole. It re-emerges as a living word-forming element mid-16c., "probably to a great extent by imitation or reminiscence of Greek compounds in (auto-)," and formed a great many words in the pamphlet disputes of the 17c.

1520s, "refusal to grant what is requested or desired;" see deny + -al (2). Replaced earlier denyance (late 15c.). Sense of "act of asserting to the contrary, contradicting" is from 1570s; that of "refusal to accept or acknowledge" is from 1580s. In some 19c. uses, it really means "self-denial." Meaning "unconscious suppression of painful or embarrassing feelings" first attested 1914 in A.A. Brill's translation of Freud's "Psychopathology of Everyday Life"; hence the phrase in denial, popularized 1980s.