Is it farther or further?
1520s, from Middle French dexterité (16c.), from Latin dexteritatem (nominative dexteritas) "readiness, skillfulness, prosperity," from dexter "skillful," also "right (hand)" (source of Old French destre, Spanish diestro, etc.), from PIE root *deks- "on the right hand," hence "south" to one facing east (cf. Sanskrit daksinah "on the right hand, southern, skillful;" Avestan dashina- "on the right hand;" Greek dexios "on the right hand," also "fortunate, clever;" Old Irish dess "on the right hand, southern;" Welsh deheu; Gaulish Dexsiva, name of a goddess of fortune; Gothic taihswa; Lithuanian desinas; Old Church Slavonic desnu, Russian desnoj). The Latin form is with the comparative suffix -ter, thus meaning etymologically "the better direction." Middle English dester meant "right hand," and in heraldry dexter means "on the right side."