verb
(transitive) To grant citizenship to someone not born a citizen.
(transitive) To acclimatize an animal or plant.
To make natural.
(transitive) To limit explanations of a phenomenon to naturalistic ones and exclude supernatural ones.
(linguistics, transitive) 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).
(transitive, intransitive) To study nature.