1. past tense and past participle of thin; made less thick, dense, or concentrated

Examples

• She thinned the paint with water before applying it to the wall.
• The sauce had thinned too much, so he added more flour.
• His hair had thinned considerably over the years.
• The crowd thinned out after the main event ended.
• The forest thinned as we approached the clearing.
• The mechanic thinned the oil to improve engine performance.