A girl that is usually 'scene' (Dresses poorly), the name comes from the Irish word meaning 'sour' or 'mean'. Most people with the name 'Caillin' are sleep deprived attention whores that date A-Z-N-S. The A-Z-N-S that she dates are usually vulnerable, weak men, who are easily whipped by this devil woman. 'Caillin' is also a more feminine name, even though used by males. Most with this name are slightly annoying and can be an extreme bitch. One might also know that Caillin is an aspiring model in the U.S.