the.com/lockkeeper

means A person who operates the gates and sluices of a canal lock, raising and lowering boats between different water levels.

from A straightforward compound of 'lock' (in the canal sense, from Old English 'loc,' meaning a barrier or enclosure) and 'keeper' (one who tends or guards something). The canal-lock meaning emerged as Europe's canal networks expanded, needing someone stationed at each chamber to work the gates and paddles by hand — the job title simply describing the job itself, with no hidden trick in its origin.