Plaintively rhymes with:
accumulatively, actively, administratively, affectively, affirmatively, aggressively, alternatively, appreciatively, assertively, attentively, attractively, authoritatively, bravely, cohesively, collectively, comparatively, competitively, comprehensively, compulsively, conclusively, consecutively, conservatively, constructively, cooperatively, creatively, cumulatively, deceptively, decisively, deductively, defensively, definitively, derisively, distinctively, dively, effectively, effusively, excessively, exclusively, exhaustively, expensively, explosively, extensively, figuratively, furtively, gravely, gravley, hively, imaginatively, impassively, impressively, impulsively, inconclusively, inexpensively, instinctively, intensively, intuitively, lavely, legislatively, lively, lovely, massively, naively, negatively, objectively, obsessively, offensively, passively, persuasively, positively, preemptively, proactively, productively, progressively, prohibitively, prospectively, protectively, provocatively, qualitatively, quantitatively, reflexively, relatively, respectively, retroactively, retrospectively, savely, seductively, selectively, sensitively, shively, shivley, sivley, snavely, snively, stavely, substantively, successively, swavely, tentatively