"Be intrinsic to" refers to something being an essential or inherent part of a particular thing. Antonyms for this phrase can be "extraneous" or "superficial," which suggests something that is not necessary or important for that thing's existence. Other antonyms that could fit within the context of opposite meanings include "irrelevant," "extrinsic," or "inessential." These words indicate that what is being referred to is not essential or fundamental to the subject at hand, highlighting its inessentiality. On the other hand, synonyms for "be intrinsic to" could include phrases like "be fundamental to," "be essential to," and "be integral to," which reflect the importance of something to a given subject or context.