Burt m
English (U.S.): of various origins. In the case of the film actor Burt Lancaster (b. 1913) it is a short form of BURTON (SEE Burton), but it has also been used as a variant spelling of BERT (SEE Bert). The pianist and composer Burt Bacharach (b. 1928) was the son of a Bert Bacharach, and his given name is presumably simply a variation of his father's.
First names dictionary. 2012.