dexterous adj.

Proto-Indo-European root meaning "right, opposite left," hence "south" (from the viewpoint of one facing east).

It forms all or part of: ambidexterity; ambidextrous; deasil; destrier; Dexter; dexterity; dexterous; dextro-.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit daksinah "on the right hand, southern, skillful;" Avestan dashina- "on the right hand;" Greek dexios "on the right hand," also "fortunate, clever;" Latin dexter "skillful," also "right (hand);" Old Irish dess "on the right hand, southern;" Welsh deheu; Gaulish Dexsiva, name of a goddess of fortune; Gothic taihswa; Lithuanian dešinas; Old Church Slavonic desnu, Russian desnoj. 

word-forming element making adjectives from nouns, meaning "having, full of, having to do with, doing, inclined to," from Old French -ous, -eux, from Latin -osus (compare -ose (1)). In chemistry, "having a lower valence than forms expressed in -ic."

1620s, alternative spelling of dexterous; this version is more conformable to Latin but less common in English.