Decorous rhymes with:
cantankerous, rancorous, adulterous, adventurous, amorous, avarice, barbarous, boisterous, cancerous, cantankerous, carboniferous, carnivorous, coniferous, dangerous, fossiliferous, generous, glamorous, hatteras, herbivorous, heterosporous, homosporous, humerous, humerus, humorous, insectivorous, lazarus, lecherous, murderous, numerous, obstreperous, odorous, omnivorous, onerous, overgenerous, oviparous, ovoviviparous, phosphorous, phosphorus, ponderous, precancerous, preposterous, prosperous, rancorous, rapturous, rhinoceros, rigorous, slanderous, sonorous, temerous, tetramerous, thunderous, timorous, traitorous, treacherous, unglamorous, uterus, vigorous, viviparous, vociferous
Decorous sounds like:
dacruz, daggers, daycares, decesaris, decker's, decourcy, decoursey, decrease, decreases, decrees, decries, degeorge, degrace, degrasse, degrazia, degrees, desires, desirous, desroches, dichroic, diego-garcia, diggers, digiorgio, digrazia, digress, digresses, disagrees, discharge, discharges, discourage, discourages, discourse, discourses, disgorge, disgrace, dishwashers, dockers, dockiers, dodger's, dodgers, dodgers', dogears, dossiers, dzhokhar's