WordWeb Online

1. Characteristic of or befitting a slut or slattern; used especially of women
   "While Scouse was at the bar, the sluttish blonde looked at us";
   - blowsy, blowzy, slatternly, slutty, tarty
    
2. Casual and unrestrained in sexual behaviour
   "her sluttish virtue";
   - easy, light, loose, promiscuous, wanton, slutty, tarty

See also: unchaste, untidy

Encyclopedia: Sluttish