plighter

plural plighters

1. One who or that which plights, engages, or pledges.

   My playfellow, your hand; this kingly seal And plighter of high hearts!

   c. 1606–1607 (date written), William Shakespeare, “The Tragedie of Anthonie and Cleopatra”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC, [Act III, scene xiii]

   2 more examples

   I mean to say, remorse has frequently been known to set in after a dust-up between a couple of troth-plighters, with all that Sorry-I-was-cross and Can-you-ever-forgive-me stuff, and love, after being down in the cellar for a time with no takers, perks up and carries on again as good as new.

   1963, P. G. Wodehouse, chapter 16, in Stiff Upper Lip, Jeeves, New York: Perennial Library, published 1983, page 124

   He hung up. And felt stupid. The most beautiful woman in the whole world had practically plighted her troth to him. And she didn’t seem like your run-of-the-mill plighter.

   1978, James Coltrane, chapter 11, in Talon, Indianapolis: Bobbs-Merrill, page 48