Billable rhymes with:
syllable, appealable, available, callable, consolable, controllable, fallible, gullible, incalculable, infallible, inhalable, inviolable, irreconcilable, noncallable, recyclable, resealable, salable, saleable, syllable, unassailable, unavailable, uncontrollable, unsalable, unsaleable, valable, violable
Billable sounds like:
baleful, belefiville, believable, bellefeuille, belleville, bellville, belveal, belville, bluebell