IPA: /ˈhændɡʌn/
KK: /ˈhændˌɡʌn/
A type of firearm that is small enough to be held and fired with one hand.
He carried a handgun for personal protection.
Handgun is formed from "hand" (from Old English "hand", meaning the part of the body at the end of the arm used for holding) and "gun" (from Middle English "gunne", possibly derived from the name of a woman, Gunhilda, who was associated with a type of cannon). The word "handgun" refers to a firearm that can be held and operated with one hand.
Think of using your 'hand' to hold a 'gun' — that's why a handgun is a firearm designed to be operated with one hand.
No commonly confused words.