"short iron bar acting as a catch or brake preventing a capstan from recoiling" (nautical) 1620s, of unknown origin; perhaps from French pal "stake" [OED] or épaule "shoulder" [Klein]. Extended to similar devices in other machinery.
pavement
paver
pavilion
Pavlovian
paw
pawl
pawn
pawnbroker
Pawnee
pawnshop
pawpaw
