IPA: /ˈsɪr.i.əs.li/
KK: /ˈsɪrɪəsli/
In a way that shows you are serious or sincere about something.
I am seriously considering moving to another city for a new job.
Seriously → It is formed from "serious" (from Latin *serius*, meaning grave or important) and the suffix "-ly" (meaning in a manner of). The word "seriously" means in a grave or important manner.
Think of something being 'grave' or 'important' ('serious') and how it is done 'in a manner of' ('-ly'). This helps you remember that 'seriously' means to do something in a serious way.