To grant citizenship to a foreigner, allowing them to become a citizen of a country. The government decided to naturalise the refugees after they had lived in the country for over five years.
To adapt or acclimatize a plant or animal to a new environment, making it capable of living and reproducing there. The botanist worked to naturalise the exotic plant species in the local ecosystem.
To make something appear natural or normal. The director aimed to naturalise the dialogue in the film to make it more relatable to the audience.