- A diminutive of the male given name Louis.
- A diminutive of the female given names Louisa and Louise; often also used as a middle name.
- 2006 Anne Tyler, Digging to America, Alfred A. Knopf, ISBN 0307263940, page 25:
- Pat and Lou, their names were. The man was Pat and the woman was Lou, or was it the other way around? Maryam knew she was going to have trouble with that.