IPA: /ˈɡlæd.sə.mli/
KK: /ˈɡlæd.sə.mli/
In a happy or joyful manner.
She accepted the award gladsomely, smiling at the audience.
Gladsomely → It is formed from "glad" (from Old English *glæd*, meaning joyful or happy) and "-some" (meaning characterized by or causing). The word "gladsomely" means in a manner that is joyful or happy.
Think of feeling 'joyful' ('glad') and being 'characterized by' that joy ('-some'). This helps you remember that to act gladsomely is to act in a joyful manner.