Etymology From Old French rivet (13th century), from the verb Old French river (“to fetter [a person]”) (12th century), from Old French rive (“rim, edge”) (ca. 1100), which is ultimately from Latin ripa (“riverbank”). Compare river, rival, riparian. The sense "kind of footman's armour" is apparently a back-formation from almain rivet, which is apparently derived from the English noun; see that entry for more.
1
A cylindrical mechanical fastener which is supplied with a factory head at one end and is used to attach multiple parts together by passing its bucktail through a hole and upsetting its end to form a field head.
Obsolete A light kind of footman's plate armour; an almain rivet.
over his rivet he had a garment of white cloth of gold with a redde crossea. 1548 (date written), Edward Hall, Richard Grafton, “(please specify the part of the work)”, in The Vnion of the Two Noble and Illustre Famelies of Lancastre & Yorke, […], London: […] Richardi Graftoni […], published 1548, →OCLC:
In 1579 it is mentioned that Almain rivets are now out of use, and in lieu of them a corselett shall be found. The rivets varied in cost; in 1509 they were to be had for 8s., in 1512 they were imported at 16s., and again in 1513 […]1903, The Archaeological Journal, page 105:
Etymology From Old French rivet (13th century), from the verb Old French river (“to fetter [a person]”) (12th century), from Old French rive (“rim, edge”) (ca. 1100), which is ultimately from Latin ripa (“riverbank”). Compare river, rival, riparian. The sense "kind of footman's armour" is apparently a back-formation from almain rivet, which is apparently derived from the English noun; see that entry for more.