Etymology
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approval (n.)
"commendation, sanction," 1680s, from approve + -al (2). According to OED, "Rare bef. 1800; now generally used instead of" approvance (1590s, from French aprovance).
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disapproval (n.)

"act or fact of disapproving, dislike," 1660s; see disapprove + -al (2), though it might as well be from dis- + approval.

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acclamation (n.)

1540s, "act of shouting or applauding in approval," from Latin acclamationem (nominative acclamatio) "a calling, exclamation, shout of approval," noun of action from past-participle stem of acclamare "to call to, cry out at, shout approval or disapproval of," from assimilated form of ad "to, toward" (see ad-) + clamare "cry out," from PIE root *kele- (2) "to shout." As a method of spontaneous approval of resolutions, etc., by unanimous voice vote, by 1801, probably from the French Revolution.

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hooya (interj.)

exclamation of triumph or approval, attested from c. 1992, perhaps originally U.S. military.

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commendation (n.)

late 14c., commendacioun, "expression of approval," late 14c. (from c. 1200 as the name of one of the Offices of the Dead), from Old French commendacion "approval, praise," from Latin commendationem (nominative commendatio) "recommendation, commendation," noun of action from past participle stem of commendare "to praise, to commit to one's care" (see commend).

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approbation (n.)

"approval, endorsement," early 15c., from Old French aprobacion "approval" (Modern French approbation) and directly from Latin approbationem (nominative approbatio) "an approval," noun of action from past-participle stem of approbare "to assent to" as good, from ad "to" (see ad-) + probare "to try, test something (to find if it is good)," from probus "honest, genuine" (see prove). Also in Middle English in a now-obsolete sense of "proven effectiveness, excellence" (late 14c.).

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plausive (adj.)

"expressing approval by or as by applause," c. 1600, from Latin plaus-, past-participle stem of plaudere "to applaud" (see plaudit) + -ive.

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gear (adj.)
"stylish, excellent," British slang, 1951 (popularized c. 1963 by the Beatles), said to be from earlier that's the gear, an expression of approval (1925), from gear (n.).
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well-done (adj.)
c. 1200, "wise, prudent," from well (adv.) + done. Meaning "thoroughly cooked," in reference to meat, is attested from 1747. Well done! as an exclamation of approval is recorded from mid-15c.
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attaboy (interj.)
1909, originally in baseball slang, said to be from common pronunciation of "that's the boy!" a cheer of encouragement or approval. I'm the boy for ______ "I'm willing and capable at" is attested from 1843. Related: Attagirl (1924).
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