IPA: /ˈdɪəˌstɔːkə/
KK: /ˈdɪrˌstɔkər/
A type of hat that fits closely to the head, featuring visors at both the front and back, and often has earflaps that can be worn up or down. It was originally designed for hunters.
He wore a deerstalker hat while walking through the woods.
Deerstalker is formed from "deer" (from Old English "deor", meaning a wild animal or deer) and "stalker" (from the verb "stalk", meaning to pursue stealthily). The word refers to a person who stealthily pursues deer, typically in hunting contexts.
Think of someone who is quietly 'pursuing' ('stalk') a 'deer' — that's why a deerstalker is someone who stalks deer.
No commonly confused words.