IPA: /ˈstrɛn.ju.əs.li/
KK: /ˈstrɛn.ju.əs.li/
In a way that requires a lot of effort, energy, or strength.
She worked strenuously to complete the project on time.
Strenuously → It is formed from "strenuus" (from Latin, meaning active or vigorous) and the suffix "-ly" (meaning in a manner of). The word "strenuously" means in a vigorous or active manner.
Think of being "active" or "vigorous" — that's what strenuously means, as it describes doing something with great energy.