Definition of Flanders mare in English:

Flanders mare

noun

  • 1A mare of a Flemish breed, typically strong and of large stature, and often used to pull coaches.

  • 2Depreciative a tall or strongly built woman (usually with the implication of unattractiveness); specifically (a nickname for) Anne of Cleves (1515–57), the fourth wife of Henry VIII.

Origin

Early 17th century; earliest use found in William Browne (1590/91–?1645), poet.