To acclimatize an animal or plant.
To make (a word) a natural part of the language, using the native homologue of each phoneme (and often for each morpheme) of the imported word (e.g., native inflections).
To study nature.
To limit explanations of a phenomenon to naturalistic ones and exclude supernatural ones.
To grant citizenship to someone not born a citizen.
To make natural
To swing indecisively from one course of action or opinion to another.
To sway unsteadily from one side to the other; oscillate.