Thelma \th(el)-ma\ as a girl's name is pronounced THEL-mah. It is of Greek origin, and the meaning of Thelma is "will, volition". A literary creation from the 19th century by Marie Corelli for the title character of her 1887 novel. The movie "Thelma and Louise" gave the name exposure.
For more information, see also the related name Velma.