surname and masc. given name, from Gaelic donn "brown, dark" (see dun (adj.)) + ceann "head." Or else from Old Irish, Old Gaelic Donnchad "brown warrior."
Entries linking to duncan
dun adj.
Old English dunn "dingy brown; dark-colored," perhaps from Celtic (compare Old Irish donn "dark;" Gaelic donn "dull; dark brown; dark;" Welsh dwnn "brownish"), from PIE *donnos, *dusnos "dark." As a noun, "dun color," 1560s; as "a dun horse" from late 14c. The "horse" meaning is that the figurative expression dun is in the mire "things are at a standstill or deadlocked," which occurs in both Chaucer and Shakespeare. Dun also is likely the origin of the surnames Dunn, Dunne, Donne, Dunning, etc.