IPA: //ˈɡlæs.mən//
KK: /ˈɡlæsˌmæn/
A person who makes or sells glass, or who installs glass in windows.
The glassman carefully fitted the new window into the frame.
The word 'glassman' is formed from 'glass' (from Old English *glæs*, meaning a transparent material) and 'man' (from Old English *mann*, meaning a human being). A glassman refers to a person who works with glass, typically in the context of glassmaking or glassblowing.
Think of a 'glass' as a transparent material and 'man' as a person who works with it — that's why a glassman is someone who works with glass.