IPA: /ɪnˈkɒmpɪtəntli/
KK: /ɪnˈkɑːmpɪtəntli/
In a way that shows a lack of skill or ability to do something properly.
He handled the project incompetently, leading to many mistakes.
Incompetently → It is formed from "in-" (meaning not) and "competent" (from Latin "competens", meaning suitable or qualified) and the suffix "-ly" (meaning in a manner). The word "incompetently" means in a manner that is not suitable or qualified.
Think of 'not' ('in-') being combined with 'suitable' ('competent') to remember that 'incompetently' means doing something in a way that is not suitable or qualified.