1. intellectual depth
penetrating knowledge
keen insight
etc

e.g. the depth of my feeling
the profoundness of the silence

Synonym: profundity

2. the quality of being physically deep

e.g. the profundity of the mine was almost a mile

Synonym: deepnessprofundity

3. the intellectual ability to penetrate deeply into ideas

Synonym: astutenessprofunditydepthdeepness

4. wisdom that is recondite and abstruse and profound

e.g. the anthropologist was impressed by the reconditeness of the native proverbs

Synonym: reconditenessabstrusenessabstrusityprofundity

5. extremeness of degree

e.g. the profoundness of his ignorance