Origin and history of tamper-proof

c. 1200, preove "evidence and argumentation to establish the fact of (something) beyond reasonable doubt," from Anglo-French prove, preove, Old French proeve, prueve "proof, test, experience" (13c., Modern French preuve), from Late Latin proba "a proof," a back-formation from Latin probare "to prove" (see prove). "The devocalization of v to f ensued upon the loss of final e; cf. the relation of v and f in believe, belief, relieve, relief, behove, behoof, etc." [OED, 2nd ed., 1989].

The meaning "act of proving" is early 14c. The meaning "act of testing or making trial of anything" is from late 14c., from influence of prove. The meaning "standard of strength of distilled liquor" is from 1705, on the notion of "having been tested as to degree of strength." The use in photography is from 1855. The typographical sense of "trial impression to test type" is from c. 1600. The numismatic sense of "coin struck to test a die" is from 1762; now mostly in reference to coins struck from highly polished dies, mainly for collectors.

The expression the proof is in the pudding (1915) is a curious perversion of earlier proof of the pudding shall be in the eating (1708), with proof in the sense "quality of proving good or turning out well" (17c.).

1560s, "meddle unwisely, interfere rashly," 1560s, a figurative use of tamper in the contemporary sense of "to work in clay, etc., so as to mix it thoroughly" (a sense now obsolete), which probably is originally a variant of temper (v.) and often was spelled temper at first. Perhaps it represents a dialectal or workmen's pronunciation (OED, 1989). Temper (v.) in the clay-working sense is attested from 14c.

It is attested by 1590s as "interfere for the purpose of alteration, make objectionably or unauthorized changes." Related: Tampered; tamperer; tampering. Tampering as a verbal noun is attested by 1854 as "improper interference."