Do you want the definition of biology?
Well using prefixes and suffixes :
-ology = study
bio- = life
so....
We can conclude it is the study of life or the study of living organisms.
The study of the organisms is based on their behavior, their body structure, their habitats, anatomy, etc. Also, it's just another word for science, it is just higher in level. Mostly highschool teaches it instead of science, and sometimes middle schools as well.
Hoped I helped!
