IPA: /ˈtɪəfəl.nəs/
KK: /ˈtɪr.fəl.nəs/
The condition of being full of tears or feeling sad and emotional.
Her tearfulness during the movie made everyone around her feel emotional too.
Tearfulness → It is formed from "tear" (from Old English *tǣr*, meaning a drop of clear salty liquid produced by glands in the eyes) and "-fulness" (meaning the state of being full of). The word "tearfulness" means the state of being full of tears or the quality of shedding tears.
Think of 'tears' as drops of liquid from the eyes, and '-fulness' means being full of something. So, tearfulness is being full of tears.