Nighthorse rhymes with:
airforce, air_force, discourse, recourse, resource, agresource, airforce, air_force, arce, bierce, borse, bourse, carse, clotheshorse, coarse, concourse, corse, counterforce, course, deadhorse, discourse, divorce, endorse, enforce, ensource, farce, fierce, force, forse, gift-horse, healthsource, hoarse, horse, intercourse, lacourse, laforce, marse, midcourse, morse, morss, norse, nourse, outsource, parse, pearce, peirce, perforce, pierce, racehorse, recourse, reinforce, remorse, resource, scarce, sorce, source, sparse, taskforce, telsource, tierce, uniforce, unisource, vorce, whitehorse, wilberforce, workforce, workhorse
Nighthorse sounds like:
negotiator's, negotiators, negotiators', nesters, newscasters, nighters, non-sequitors