open-kneed

adjective1

1. •
   (historical) Having wide legs and reaching below the knees but higher than the ankles (not tied or closed at the knees).

   • He had on no Cloaths, but a Seaman’s Wastcoat, a Pair of open-knee’d Linnen Drawers, and a blew Linnen Shirt; but nothing to direct me so much as to guess what Nation he was of […] — 1719