"Lock keeper" refers to a person responsible for operating and maintaining canal or river locks. However, this term may have different synonyms depending on the location, culture, and language. In some regions, they are called "lock tender," "lock operator," "canal keeper," or "lock manager." In the British Isles, they were once known as "lock-wardens" or "lock-keepers." Other countries use different names like "eclusier" in France, "sluismeester" in the Netherlands, and "Schleusenwärter" in Germany. Regardless of the title, their job remains the same, to ensure the smooth and safe passage of boats through the locks. Synonyms for "lock keeper" provide an understanding of how this occupation plays a crucial role in maintaining the integrity of inland waterways transportation systems.