illusive, holy grail, unattainable, enigmatic, unachieved, improbable, nebulous, attainable, vexed, unobtainable, ephemeral, mythical, alluring, unreachable, tantalizing, irresistible, illusory, coveted, inscrutable, fabled, chimerical, fleeting, true, indefinable, rarer, fruitless, intractable, ultimate, unfulfilled, unaccomplished, improvable, daunting, impossible, prized, magical, impenetrable, tricky, allusive, loftier, stealthy, thorny, ineffable, transcendent, definitive, tenuous, ageless, fangless, intriguing, obscure, perplexing, nettlesome, uncanny, satisfying, imperfect, exasperating, evasive, tempting, magic bullet, unstoppable, unlikely, tenacious, solitary, peskiest, unflappable, potent, tractable, blackburnian warbler, fugitive, puzzling, indispensable, murkiest, knotty, mythic, enrapturing, undefinable, futile, troublesome, crucial, mysterious, fearsome, unknowable, unanswerable, invisible, unachievable, scarce, achievable, alive, captivating, prolific, restless, unsatisfying, graspable, mot juste, irrepressible, unvanquished, ubiquitous, embraceable, loquacious, resourceful, wily, sisyphean, omnipresent, protean, incorporeal, unsettling, immaterial, problematical, troubling, intangible, intuited, numinous, objectified, disembodied, existent, knowable, mystifying, problematic

artful, impalpable, subtle, unidentifiable