cavalryman / cavalrymen are similar-sounding terms with different meanings (referred to as homophones). To better understand the differences, see below for definitions, pronunciation guides, and example sentences using each term. 👇
cavalryman: (noun) a soldier in a motorized army unit. (noun) a soldier mounted on horseback.
cavalrymen: (noun) a soldier in a motorized army unit. (noun) a soldier mounted on horseback.
cavalryman: NA
cavalrymen: NA
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)