Definitions
1.VerbTo grant citizenship to someone not born a citizen.
2.VerbTo acclimatize an animal or plant.
3.VerbTo make natural."Custom naturalizes labour or study."
4.VerbTo limit explanations of a phenomenon to naturalistic ones and exclude supernatural ones.
5.VerbTo 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)."; In English, foreign words are typically written in italics until they are naturalized.; English speakers have naturalized the French word "café".; English orthography often (but not invariably) drops the diacritics from words that it has naturalized from other languages."
6.VerbTo study nature.
7.Verb↑ "naturalize" in Dictionary.com Unabridged. Random House, Inc.