What does Keelan mean? Keelan [kee-lan] as a boys' name (also used less widely as girls' name Keelan) is of Irish and Gaelic origin, and the meaning of Keelan is slender. Associated with: irish, slender (little). Keelan has 6 variants: Kealan, Keallan, Keallin, Keilan, Keillan and Kelan.