also: はしこい
i-adjective
Describes a person who is mentally quick, sharp-witted, or shrewd, often with a nuance of being street-smart or crafty.
あの子ははしっこくて、すぐに答えを見つける。
That kid is sharp and finds the answer right away.
He's shrewd, so he won't be fooled.
i-adjective
Describes physical quickness and agility; can also refer to mental quickness in some contexts, but primarily physical nimbleness.
猫ははしっこくて、高いところにも簡単に登る。
Cats are nimble and easily climb to high places.
彼ははしっこい動きで相手をかわした。
He dodged his opponent with quick movements.