Definitions

1. noun

opposite direction; the other side of a ship or boat, esp. when it is sailing or being steered across the wind.

“The captain steered the ship athwart the waves.”

2. adverb

crosswise; at right angles to something.

“The rope was stretched athwart the beam, supporting the weight.”

3. preposition

across something; opposite something.

“The road runs athwart the river.”