Donald is a masculine given name derived from the Gaelic name Dòmhnall. This comes from the Proto-Celtic *Dumno-ualos ("world-ruler" or "world-wielder"). The final -d in Donald is partly derived from a misinterpretation of the Gaelic pronunciation by English speakers, and partly associated with the spelling of similar-sounding Germanic names, such as Ronald. A short form of Donald is Don. Pet forms of Donald include Donnie and Donny. The feminine given name Donella is derived from Donald.

Donald has cognates in other Celtic languages: Modern Irish Dónal (anglicised as Donal and Donall); Scottish Gaelic Dòmhnall, Domhnull and Dòmhnull; Welsh Dyfnwal and Cumbric Dumnagual. Although the feminine given name Donna is sometimes used as a feminine form of Donald, the names are not etymologically related.