Superjacent means lying above or on top of something else.
The word superjacent is used in formal or technical situations, like in science or architecture.
Examples:
The superjacent layer of rock is very hard.
The superjacent book is on top of the other books.
The superjacent clouds are very high in the sky.
The superjacent cat is on top of the table.
The superjacent mountain is the tallest in the world.
The superjacent roof keeps the rain out.