The family Sciuridae includes small or medium-sized rodents which include tree squirrels, ground squirrels (including chipmunks and prairie dogs, among others), and flying squirrels...

Rodentia is from Latin for rodens 'gnawing'.

Sciuridae: from Latin Sciurus which is from the Ancient Greek word σκίουρος (skiouros; from σκιᾱ́ ('shade') and οὐρᾱ́ ('tail')),referring to the long bushy tail which many of its members have.

The word squirrel comes from the Anglo-Norman esquirel which is from the Old French escureil, the reflex of a Latin word sciurus.