"British soldier," 1884, from Thomas Atkins, since 1815 the sample name for filling in army forms. Tommy gun (1929) is short for Thompson gun (see Thompson). Soon extended to other types of sub-machine gun, especially those favored by the mob.
every tom* dick* and harry
Stupid; foolish; nutty: some tomfool scientist
[1762+; found by 1356 as the actual name of a man, also called Thomas fatuus, ''foolish Tom'']