The quality or state of being fitted; the condition of being appropriately suited or adjusted to fit.
From 'fitted' (past participle of fit, meaning appropriately suited) plus '-ness' (quality or state), creating an abstract noun. Follows standard nominalization patterns in English.
The fittedness of a dress after alterations—that perfect sense that everything is exactly where it should be—is something tailors strive for, and it's measurable in how comfortable it feels.
Complete word intelligence in one call. Free tier — 50 lookups/day.