A more thorough explanation:

Definition: Adjacent (adj.) means something is near or close to another thing, but they may not be touching each other. It is similar to but not the same as adjoining.

Examples:

• The hotel room next to mine was empty, so I had no adjacent neighbors.
• The two houses were adjacent to each other, but there was a small garden between them.
• The park is adjacent to the school, so the students often go there for recess.

The first example shows that adjacent can mean that there is nothing between two things, like the empty hotel room. The second example shows that adjacent can mean that there is something between two things, like the garden between the houses. The third example shows that adjacent can also be used to describe the relationship between places, like the park and the school.