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to flip; to snap; to flick
to repel
to use (an abacus); to calculate
to strum; to pluck the strings (of a guitar, etc.)
指でコインをはじいた。
I flicked a coin with my finger.
ギターの弦を指で弾いた。
I plucked the guitar string.
水をはじく素材だから安心。
It repels water so no worries.