Definition from Wiktionary, the free dictionary
underkeeper (plural underkeepers)
- (obsolete) A subordinate keeper or guardian.
1897, James D. Richardson, A Compilation of the Messages and Papers of the Presidents:
- By the letter of the judges of the circuit court of the United States, held at Boston in June last, and the inclosed application of the underkeeper of the jail at that place, of which copies are herewith transmitted, Congress will perceive the necessity of making a suitable provision for the maintenance of prisoners committed to the jails of the several States under the authority of the United States.