IPA: /əˈtæʧər/
KK: /əˈtæʧər/
A person or device that connects or fastens things together.
The attacher helped secure the banner to the wall for the event.
Attacher is formed from "attacher" (from Old French, meaning to fasten or bind) and the suffix "-er" (meaning a person who). The word "attacher" refers to a person who fastens or binds something.
Think of someone who 'fastens' or 'binds' things together — that's what an 'attacher' does.