/pen"i treuhnt/ , n.
1. a person or thing that penetrates.
2. a compound that penetrates the skin, as a lotion or cream.
3. a substance that lowers the surface tension of water; wetting agent.
4. Zool. a large nematocyst discharging a barbed thread that penetrates the body of the prey and injects a toxic fluid.
adj.
5. penetrating.
[ 1535-45; penetrant- (s. of penetrans ), prp. of penetrare to PENETRATE; see -ANT ]