skainsmate

Etymology and meaning uncertain. Possibly from skean (“sword”) or skein (“quantity of thread”) +‎ -s- +‎ mate (“companion; comrade; colleague”).

• Sword could imply a companion in arms or a cutthroat; or it may be a euphemism for penis and hence a sexual companion.
• Thread could also mean either a companion in winding thread, possibly a sailor or seamstress, or a sexual metaphor equating sewing with sexual intercourse.

Flirt-gill (“promiscuous woman”) in the same passage suggests a sexual interpretation.

skainsmate (plural skainsmates)

1. (obsolete, derogatory, nonce word) A messmate; a companion.
2. (obsolete, derogatory, nonce word) A prostitute.

• c. 1591–1595, William Shakespeare, Romeo and Juliet, act 2, scene 4, lines 149–151:

  Scurvy knave! I am none of his flirt-gills; I am none of his skainsmates.

• “skainsmate n.”, in Oxford Reference‎, 2018 February 20 (last accessed)