Troth, a somewhat archaic term meaning "loyalty" or "faithfulness," has several synonyms that capture this meaning. One of the most fitting is "fidelity," which suggests steadfastness and commitment. "Devotion" is another word that conveys a deep and abiding sense of loyalty, while "allegiance" implies a strong sense of obligation or duty. "Constancy" captures the idea of unwavering faithfulness, while "steadfastness" suggests a firm and resolute commitment. Finally, "fealty" is a slightly more formal alternative to "troth," evoking loyalty and commitment to a higher authority or cause. Overall, there are many words that can convey the sense of unwavering loyalty and faithfulness implied by the word "troth".