From Longman Dictionary of Contemporary Englishtrothtroth /trəʊθ $ trɒːθ, trɑːθ, troʊθ/ noun → plight your troth at plight2
Examples from the Corpus
troth• We will continue to cry at weddings because we know how bittersweet, how fragile is the troth.• Of course, if everyone knew their partners inside out, there's a good chance no-one would ever plight their troth.Origin troth (1200-1300) truth 