pheromone

definition: 
A chemical substance produced and released into the environment by an animal, especially a mammal or an insect, affecting the behaviour or physiology of others of its species.
sentence: 
Once an enterprising hornet scouts out a bee colony, it marks the nest with a type of bodily chemical substance called a pheromone.
difficulty: 
medium
toefl frequency: 
1
toefl classification: