1. Becoming gradually less dense or numerous
   "His thinning hair revealed more scalp each year"

1. Make less dense, numerous or viscous
   "Thin the solution"; "They thinned the forest to prevent fires"
    
2. Lose thickness; become thin or thinner
   "The crowd thinned as the night wore on"
    
3. Lessen the strength or flavour of a solution or mixture
   "She thinned the paint with water";
   - dilute, thin out, cut
    
4. Lose weight quickly or effortlessly
   "She thinned down over the summer";
   - melt off, slim, slenderize, slim down, slenderise [Brit], lose weight

Type of: bring down, change state, cut, cut back, cut down, reduce, trim, trim back, trim down, turn, weaken

Antonym: inspissate

Encyclopedia: Thinning