WordNet sense 1 (a strand or cluster of hair):

curl, ringlet, whorl

WordNet sense 2 (enclosure consisting of a section of canal that can be closed to control the water level; used to raise or lower vessels that pass through it):

lock chamber

WordNet sense 3 (a restraint incorporated into the ignition switch to prevent the use of a vehicle by persons who do not have the key):

ignition lock

WordNet sense 4 (hold in a locking position):

interlace, interlock

WordNet sense 5 (keep engaged):

engage, mesh, operate

WordNet sense 6 (place in a place where something cannot be removed or someone cannot escape):

lock in, lock up, put away, lock away, shut away, shut up