Opiates rhymes with:
affiliates, associate's, associates, associates', chariots, cheviots, ciliates, compatriots, cypriots, eliot's, elliott's, idiots, initiates, intermediates, laureates, marriott's, patriot's, patriots
Opiates sounds like:
obits, obtuse, obviates, opdyke, opitz, optek, optic, optica, optics, opts, optus, ovett's, oviatt's, ovitt's, ovitz, ovitz's