adverb
From side to side, often in an oblique manner; across or over.
Across the path of something, so as to impede progress.
(figuratively) Against the anticipated or appropriate course of something; improperly, perversely, wrongly.
preposition
From one side to the other side of; across.
Across the course or path of, so as to meet; hence (figuratively), to the attention of.
Across the course or path of, so as to oppose.
Across; through.
Opposed to.
(nautical) Across the line of a ship's course, or across its deck.