thin, fine, attenuated, flimsy, unsubstantial, minute

difficult

one who bruises, brays, or pounds

difficulties, subtleties

complete fool

intelligent, sharp-minded

kind-hearted, one who easily gets emotional

comprehending nice or abstruse points, impassioned penetrating, discerning, of quick apprehension

difficult arguments

sharp, clever

nuances of a craft

leave no stone unturned

the planet Venus

highly emotional and tearful, highly emotive and tear-jerking

discernment, minuteness, perspicacity

get into trouble or difficulty

quick of apprehension, penetrating, discerning

discerning, penetrating, quick of apprehension, perspicacious

a second, a moment, very brief span of time

do one's very best, leave no stone unturned

a disease in which the sperm becomes thin or dilute

thinness, liquidity