nounan iron or wooden grating suspended vertically in grooves in the gateway of a castle or fortified town and able to be lowered so as to bar the entrance
 Word origin
C14 
port colice, from Old French 
porte coleïce sliding gate, from 
porte door, entrance + 
coleïce, from 
couler to slide, flow, from Late Latin 
cōlāre to filter