The term dyke has been used to refer to lesbians since the 1920s and probably earlier than that. While it used to be a demeaning word that was used as a slur, it has since been approapriated by a number of gay women to imply toughness and being assertive, eg. there have been many Dyke Marches as part of Gay Pride events. A bull dyke or diesel dyke refers to a lesbian who appears masculine or manly; AKA butch. Opposing terms are lipstick lesbian, high femme, and femme.