The name is possibly derived from the Gaelic elements còil ("nook"), cùil ("corner"), or coill(e) ("wood") + cumhann ("narrow"), or comh-thonn ("wave crash").
Phonetically, MacOlquhoun is similar to MacElhone/MacIlhone and therefore Colquhoun may sometimes derive from the Gaelic name Mac Giolla Còmhghan.
[3] Còmhghan is derived from comh ("together") and gan-, gen- ("born").
[4] Calhoun, Colhoun, Calhoon, Colhoon, Cohoon, Hoon, Cahoun, and Cahoon are variants of the surname Colquhoun.
They are generally found as simplifications and respellings, though all of them can occur from unrelated sources.