álabe

olive branch bent down and reaching the ground; any of the force-transmitting elements of a propelling wheel in a water-mill, flier, vane; turbine blade; windmill sail; tappet on a fulling wheel; a barrier such as a mat on the side of a carriage so he who drives it does not fall out

Uncertain. Perhaps Latin ālipēs (“winged”) or alapa (“blow, smack”). Compare Romanian aripă (“vane”).