WordWeb Online

1. Become more extreme
   "The tension heightened";
   - rise
    
2. Make more extreme; raise in quantity, degree, or intensity
   "heightened interest"
    
3. Add something extra to make more intense or better
   "heighten the tension";
   - enhance, raise, increase
    
4. Increase the height of
   "The athletes kept jumping over the steadily heightened bars"
    
5. Make (one's senses) more acute
   "This drug will heighten your vision";
   - sharpen
    
6. Make more intense, stronger, or more marked
   "Pot smokers claim it heightens their awareness";
   - intensify, compound, deepen

Derived forms: heightened, heightening, heightens

Type of: bring up, elevate, get up, increase, lift, raise