The word biology entered its modern usage in 1802, a combination of the Ancient Greek words bios meaning life and the common suffix logos, to denote the study of. The German naturalist Gottfried Reinhold Treviranus and the French naturalist Jean Baptiste Lamarck both published volumes on natural history using the word and it quickly found its way into English.
Today the science of biology has dozens of subsets: molecular biology, evolutionary biology, human biology, bio-technology, cell biology, marine biology and even extreme biology and exobiology, both devoted to life forms that exist in extreme environments or the search for evidence of extraterrestrial life.
Image of Antarctic diatoms by Professor Gordon T. Taylor of NOAA. Image in the public domain.