IPA: /ˈbʌtənˌhoʊlər/
KK: /ˈbʌtənˌhoʊlər/
A person or machine that creates buttonholes, which are small openings in fabric for buttons to pass through.
The tailor used a buttonholer to quickly make buttonholes on the new shirt.
Buttonholer → It is formed from "button" (from Old French *bouton*, meaning a small knob or button) and "-holer" (from "hole" with the suffix "-er" indicating a person who does something). A buttonholer is a person who makes or works with buttonholes, specifically in sewing or tailoring.
Think of a person who creates 'holes' for 'buttons' — that's what a buttonholer does.
No commonly confused words.