Definitions of across:

• adjective:   placed crosswise

  Example: "Seated with arms across"

• adverb:   transversely

  Example: "The marble slabs were cut across"

• adverb:   to the opposite side

  Example: "The football field was 300 feet across"

• adverb:   in such a manner as to be understood and accepted

  Example: "She cannot get her ideas across"