Adjacent

1. Lying next to, close, or contiguous; neighboring; bordering on.

Synonyms: abutting, adjoining, contiguous, juxtaposed, near

Antonyms: apart, distant, nonadjacent

2. Just before, after, or facing
3. (figuratively, postpositive) Related to; suggestive of; bordering on.

1. Next to; beside.

2. (figuratively) Related to; suggestive of; bordering on.

This preposition is usually used with the word to, i.e., "adjacent to". However, in the U.S., adjacent is sometimes used on its own