1. pensiveness(n = noun.feeling) brooding - persistent morbid meditation on a problem;
is a kind of melancholy
Derived form adjective pensive1
2. pensiveness(n = noun.attribute) contemplativeness, meditativeness - deep serious thoughtfulness;
is a kind of thoughtfulness
Derived form adjective pensive2
The state of being pensive; serious thoughtfulness; seriousness. Hooker. [1913 Webster]