grimalkin

In the opening scene of William Shakespeare's Macbeth, one of the three witches planning to meet with Macbeth suddenly announces, "I come, Graymalkin." The witch is responding to the summons of her familiar, or guardian spirit, which is embodied in the form of a cat. Shakespeare's graymalkin literally means "gray cat." The gray is of course the color; the malkin was a nickname for Matilda or Maud that came to be used in dialect as a general name for a cat—and sometimes a hare—and for an untidy woman as well. By the 1630s, graymalkin had been altered to the modern spelling grimalkin.