late 15c., "act of avenging, revenge," from Old French vindicacion "vengeance, revenge" and directly from Latin vindicationem (nominative vindicatio) "act of claiming or avenging," noun of action from past participle stem of vindicare "lay claim to, assert; claim for freedom, set free; protect, defend; avenge" (related to vindicta "revenge"), probably from vim dicare "to show authority," from vim, accusative of vis "force" (see vim) + dicare "to proclaim" (from PIE root *deik- "to show," also "pronounce solemnly," and see diction). Meaning "justification by proof, defense against censure" is attested from 1640s.
French, "God and my right," the watchword of Richard I at the Battle of Gisors (1195), adopted as the motto on the royal arms of England. The "right" was Edward's claim to the crown of France upon the death of his uncle, Charles the Fair, king of France, without male issue.
"quality of being credible, capacity or condition of being believed, just claim to credit," 1590s, from Medieval Latin credibilitas, from Latin credibilis (see credible). Credibility gap is 1966, American English, in reference to official statements about the Vietnam War.
"belief, trust in facts derived from other than personal knowledge; that which gives a claim to belief," mid-14c., from Medieval Latin credentia "belief," from Latin credentum (nominative credens), past participle of credere "believe, trust" (see credo).
late 14c., "give up (something), surrender, abandon, submit; relinquish (an office, position, right, claim)," from Old French resigner "renounce, relinquish" (13c.), from Latin resignare "to check off, annul, cancel, give back, give up," from re-, here perhaps denoting "opposite" (see re-), + signare "to make an entry in an account book," literally "to mark," from Latin signum "identifying mark, sign" (see sign (n.)).
The notion is of making an entry (signum) "opposite" — on the credit side — balancing the former mark and thus canceling the claim it represents. The specific meaning "give up a position" also is from late 14c. The sense of "to give (oneself) up to some emotion or situation" is from 1718. Related: Resigned; resigning.