Preposition

1. To, toward or from the far side of.

   We rowed across the river

   Fortunately, there was a bridge across the river

   He came across the street to meet me

2. On the opposite side of.

   That store is across the street

3. From one side to the other.

   The meteor streaked across the sky

4. Bridging a gap

   This poetry speaks across the centuries

5. perpendicularly

   Lay the top stick across the bottom one

Adverb

1. From one side to the other.

   She helped the blind man across.

   The river is half a mile across.

2. On the other side.

   If we sail off at noon, when will we be across?.

3. In a particular direction.

   He leaned across for a book.

4. Horizontally.

   I got stuck on 4 across.