Detentions rhymes with:
attentions, contentions, extensions, pretensions, apprehensions, attentions, contentions, convention's, conventions, dimensions, extensions, inventions, mentions, pensions, pretensions, suspensions
Detentions sounds like:
daunting, demanding, demotions, denomination's, denominations, denoting, denting, denuding, detonating, detonations, dominating, donating, donations, downtown's, downtowns