Unknown origin. There are several theories, none with much evidence.
Perhaps from Proto-Germanic *dukkǭ (“power, strength, muscle”) + diminutive suffix -ga, probably meaning "little dynamo" in the original sense. Akin, if so, to Old English -docce (“muscle”); compare fingerdocce (“finger-muscle”).
docga m (nominative plural docgan)
- Only attested once, where genitive plural docgena glosses Latin canum.