Mckinley /mc-kin-ley/ [3 sylls.] as a boys' name is of Gaelic, Scottish and Irish derivation, and the meaning of Mckinley is son of the white warrior; learned ruler.Mckinley is an alternate form of Mackinley (Gaelic). Mckinley is also a form of Mc- (Scottish, Irish): surnames occasionally used as given names.ckinley /mc-kin-ley/ [3 sylls.] as a boys' name is of Gaelic, Scottish and Irish derivation, and the meaning of Mckinley is son of the white warrior; learned ruler.