Definition from Wiktionary, a free dictionary

digitus manūs (digit of the hand)

From Proto-Indo-European *diǵ-, zero-grade of *deyǵ- (“‘to show, point out, pronounce solemnly’”), variants of roots *diḱ-, *deyḱ- that also gave Latin dīcō (“‘I say, speak talk’”). Fingers where thus "pointers, indicators". Digit sense comes from the fact that they were used for counting up to ten.

Indo-European cognates include Sanskrit दिशति (diśáti), “‘to show, point out’”), Ancient Greek δείκνυμι (deiknumi), “‘to show’”), δίκη (dikē), “‘manner, custom’”), Old English tǣċan (“‘to show, point out’”) (English teach) and tācen (English token).

Compare similar semantic shift in English in the cognate word teacher (“‘forefinger, index finger’”).

• (Classical) IPA: /ˈdi.gi.tʊs/
•  Audio (Classical)^{help, file}

digitus (genitive digitī); m, second declension

1. a finger, toe, digit
2. a twig