From The Collaborative International Dictionary of English v.0.48:
Slut \Slut\ (sl[u^]t), n. [OE. slutte; cf. OD. slodde a slut, Icel. sl["o]ttr a heavy, loglike fellow, slota to droop.] 1. An untidy woman; a slattern. [1913 Webster]
Sluts are good enough to make a sloven's porridge. --Old Proverb. [1913 Webster]
2. A servant girl; a drudge. [Obs.] [1913 Webster]
Our little girl Susan is a most admirable slut, and pleases us mightily, doing more service than both the others. --Pepys. [1913 Webster]
3. A female dog; a bitch. [1913 Webster]