the world > physical sensation > hearing and noise > degree, kind, or quality of sound > sharp or hard sound > [verb (transitive)] > crack or snap > the fingers (3)
intransitive. To make a noise with thumb and finger which resembles the whispering of ‘thrip’ or ‘flip’; transitive to snap (the fingers). Obsolete.
transitive and intransitive. To snap, or crack lightly (the fingers, etc.); to ‘knack’ lightly.
To cause (the fingers) to make a sharp noise by striking against the ball of the thumb, esp. as a sign of delight or contempt. Also figurative.