one's darnedest (noun) attempt: try, effort
Sinonime: all, entire, exhaustive, faultless, full, full-dress, gross*, hook line and sinker, imperforate, intact, integral, integrated, lock stock and barrel, organic, outright, plenary, replete, the works, thorough, thoroughgoing, unabridged, unbroken, uncensored, uncondensed, uncut, undiminished, undivided, undocked, unexpurgated, unimpaired, unitary, unreduced, whole, whole enchilada, whole nine yards, whole-hog, whole-length
Antonime: certainty,
laziness,
success