IPA: /ˈskɜːrmɪʃər/
KK: /ˈskɜrmɪʃər/
A soldier who fights in small groups, often in a light and flexible manner, usually to engage the enemy in a quick and informal way.
The skirmisher moved ahead of the main troops to gather intelligence on the enemy's position.
Skirmisher → It is formed from "skirmish" (from Middle French *eskirmir*, meaning to fight or engage in a skirmish) and "-er" (meaning a person who). A skirmisher is a person who engages in a minor battle or skirmish.
Think of someone who 'fights' ('eskirmir') in a small battle — that's what a skirmisher does.