acuteness

Short definition from Wiktionary

Noun

1. 1
   The quality of being acute or pointed
2. 2
   The faculty of precise discernment or perception; sensitiveness
3. 3
   Shrillness; high pitch; – said of sounds.
4. 4
   Violence of a disease, which brings it speedily to a crisis.
5. 5
   Shrewdness, quickness of mind