Longman Dictionary of Contemporary English
life form
noun
EXAMPLES FROM CORPUS
▪ In the biosphere, the more elaborate the structure, the higher the life form.
▪ It is, therefore, the complementary life form to the animals of Earth.
▪ The people on the ship have to create an artificial life form because their computer has failed.
Wiktionary
life form
n. 1 The morphology of an organism that distinguishes it from others. 2 (alternative form of lifeform English)
WordNet
life form
n. the characteristic bodily form of a mature organism