IPA: /əˈtæʧəbl/
KK: /əˈtæʧəbl/
Capable of being fastened or joined to something else.
The new accessories are easily attachable to the main device.
Attachable → It is formed from "attach" (from Old French *atachier*, meaning to fasten or join) and "-able" (meaning capable of). The word "attachable" means capable of being fastened or joined.
Think of something that can be 'fastened' ('attach') — the '-able' means it can be done. So, attachable means it can be fastened.