IPA: /ˈmɜːrθfəl/
KK: /ˈmɜrθfəl/
Full of joy and happiness; showing or expressing laughter and cheerfulness.
The children were mirthful as they played in the sunny park.
Mirthful → It is formed from "mirth" (from Old English *myrth*, meaning joy or amusement) and "-ful" (meaning full of). The word "mirthful" means full of joy or amusement.
Think of 'mirth' as joy and remember that 'mirthful' means full of joy.