IPA: /ˈpɑːrtli/
KK: /ˈpɑrtli/
To a certain extent, but not completely; in some way or degree.
The project was partly successful, but there were still some issues to address.
Partly → It is formed from "part" (from Old French *part*, meaning a portion or division) and "-ly" (meaning in a manner of). The word "partly" means in a manner that is a portion or to some extent.
Think of a 'part' as a portion of something, and '-ly' indicates the manner. So, 'partly' means something is true to a certain extent or in part.