late 14c., renouncen, "give up (something, especially to another), resign, surrender," from Old French renoncier "give up, cede" (12c., Modern French renoncer) and directly from Latin renuntiare "bring back word; proclaim; protest against, renounce," from re- "against" (see re-) + nuntiare "to report, announce," from nuntius "messenger" (from PIE root *neu- "to shout").
The sense of "abandon, discontinue" (a habit, practice, etc.) is from late 15c.. That of "disclaim relationship with or allegiance to" a person is by c. 1500. That of "to abandon or give up" a belief, opinion, etc. by open recantation, declare against" is from 1530s. Related: Renounced; renouncing; renouncement.
Renounce, to declare strongly, with more or less of formality, that we give up some opinion, profession, or pursuit forever. Thus, a pretender to a throne may renounce his claim. Recant, to make publicly known that we give up a principle or belief formerly maintained, from conviction of its erroneousness ; the word therefore implies the adoption of the opposite belief. [Century Dictionary]
"believable, worthy of belief, capable of being believed, involving no impossibility; of known or obvious veracity or competence," late 14c., from Latin credibilis "worthy to be believed," from credere "to believe" (see credo). Related: Credibly.
mid-15c., "the proving or finding of guilt of an offense charged," from Late Latin convictionem (nominative convictio) "proof, refutation," noun of action from past-participle stem of convincere "to overcome decisively," from com-, here perhaps an intensive prefix (see com-), + vincere "to conquer" (from nasalized form of PIE root *weik- (3) "to fight, conquer").
Meaning "mental state of being convinced or fully persuaded" is from 1690s; that of "firm belief, a belief held as proven" is from 1841. In a religious sense, "state of being convinced one has acted in opposition to conscience, admonition of the conscience," from 1670s.
"act of misleading someone, deception, deceit," early 15c., delusioun, from Latin delusionem (nominative delusio) "a deceiving," noun of action from past-participle stem of deludere (see delude). As a form of mental derangement, "false impression or belief of a fixed nature," 1550s.
Technically, delusion is a belief that, though false, has been surrendered to and accepted by the whole mind as a truth; illusion is an impression that, though false, is entertained provisionally on the recommendation of the senses or the imagination, but awaits full acceptance and may not influence action. Delusions of grandeur, the exact phrase, is recorded from 1840, though the two words were in close association for some time before that.
"correctness of opinion," especially in theology; "conformity to the Church creeds," 1620s, from French orthodoxie and directly from Late Latin orthodoxia, from late Greek orthodoxia "right opinion," abstract noun from orthodoxos "having the right opinion" (see orthodox). Orthodoxies "correct belief or opinion" is by 1871.