IPA: /ˈkræks.mən/
KK: /ˈkræksmən/
A person who breaks into buildings to steal things, often using tools to unlock doors or windows.
The police caught the cracksman trying to break into the jewelry store.
Cracksman → The word is formed from "crack" (from Middle English *crakken*, meaning to break or shatter) and "-sman" (a suffix denoting a person associated with a particular activity). A cracksman is thus a person who is skilled in breaking into places, particularly in the context of burglary.
Think of someone who is skilled at 'breaking' ('crack') into places — that's why a cracksman is a person who breaks in.