Underrate rhymes with:
overrate, berate, crate, desecrate, frate, freight, grate, great, irate, mccreight, overrate, prorate, rait, raitt, rate, straight, strait, strate, streight, trait
Underrate sounds like:
underrated, undertow, underwood, underwrite, underwrote, undeterred, unhindered, unitrode, untoward, untreated, untried, untruth