IPA: /ˈtrʌbəlˌsʌmli/
KK: /ˈtrʌbəlˌsʌmli/
In a way that causes problems or difficulties.
The project was progressing troublesomely, with many unexpected issues arising.
Troublesomely → It is formed from "trouble" (from Old French *trouble*, meaning disturbance or confusion) and the suffix "-some" (meaning characterized by) combined with the adverbial suffix "-ly" (meaning in a manner). The word "troublesomely" means in a manner characterized by disturbance or causing trouble.
Think of 'trouble' as a disturbance and remember that 'troublesomely' means acting in a way that causes disturbance.