Green’s Dictionary of Slang

skainsmate n.

[ety. unknown; see cit. 1595. The context seems to indicate a prostitute; ult. ? dial. skain, a dagger; thus fig. a penis or skein of thread or wool, and thus relates to the ‘sewing’ imagery of intercourse; Nares, Glossary (1822), is ‘inclined to think that the old lady [i.e. the nurse speaking in the cit.] means “roaring or swaggering companions”’]

a prostitute.

[UK]Shakespeare Romeo and Juliet II iii: nurse: I am none of his flirt-gills; I am none of his skainsmates.