the quality or state of being engaged; the degree of attention, participation, or commitment someone shows.
From engaged + -ness (noun-forming suffix creating abstract nouns from adjectives). The suffix -ness is from Old English -nes.
Psychology and education research measures 'student engagedness' as a predictor of success—a single word that became scientifically crucial in understanding how people learn.
Complete word intelligence in one call. Free tier — 50 lookups/day.