keymanEtymologyFrom key + man.nounA telegraph operator.“Conscious of their importance, the 324 labor delegates marched bravely in and elected by acclaim as their president a onetime Ontario telegraph keyman, Senator Gideon Decker Robertson […]”A workman who checks a railway track for faults, and who carries a keying hammer.An employee of vital importance to a business.“A corporation may feel the need for life insurance on one of its keymen under a variety of circumstances.”