From The Collaborative International Dictionary of English v.0.48 [gcide]:
Whoremaster \Whore"mas`ter\, n.
1. A man who practices lewdness; a lecher; a whoremonger.
[1913 Webster]
2. One keeps or procures whores for others; a pimp; a
procurer.
[1913 Webster]
From WordNet (r) 3.0 (2006) [wn]:
whoremaster
n 1: a prostitute's customer [syn: whoremaster, whoremonger,
john, trick]
2: a pimp who procures whores [syn: whoremaster,
whoremonger]