"It's an Anglicized spelling used in a lot of placenames in Ireland. It's usually either a corruption of the Gaelic words coill meaning 'wood' (as in a small forest), cill meaning 'church' or caoile meaning 'narrow' (as in a strait, a narrow pass or passage).

"As a person's name it's not a traditional one. It's been adopted from the 'Kyle' in these Anglicized placenames, so you can pretty much take your pick as to which original interpretation you prefer."