Balloonist rhymes with:
opportunist, abortionist, africanist, agonist, anticommunist, brownest, collaborationist, colonist, constitutionist, constructionist, earnest, expansionist, extortionist, funnest, greenest, humanist, hygienist, internist, interventionist, leninist, misogynist, noncommunist, nutritionist, opportunist, percussionist, peronist, preservationist, protectionist, receptionist, rejectionist, religionist, reservationist, revisionist, revolutionist, satanist, saxophonist, secessionist, segregationist, stalinist, tannest, thinnest, trombonist, zionist
Balloonist sounds like:
balanced, belonged, blancett, blanchet, blanchett, blanchette, blanked, blanket, blanketed, blanquita, blansett, blemished, blinked, blomquist, bloomquist, blumquist