across = from one or more ends to another or more It can be one dimensional - across the street two dimensional - across the country three dimensional - across the universe multidimensional - across many dimensions (used in mathematics or Star Trek)

Usually, I think "across" can be replaced with "from one side to the other [of]". I ran across the street. He travelled across Europe. There was a bridge across the river. She lived across the street from me. - [she lived directly on the opposite side of the street, from one side to the other without any distance up or down the street] He looked across the aisle at me. The hole was two meters across.

Usually, I think "across" can be replaced with "from one side to the other [of]". I ran across the street. He travelled across Europe. There was a bridge across the river. She lived across the street from me. - [she lived directly on the opposite side of the street, from one side to the other without any distance up or down the street] He looked across the aisle at me. The hole was two meters across.

Across has several meanings. One meaning would be the traversal or crossing of something. "He has walked across the desert." Another meaning would indicate the length of something: "The room is 3 meters across." Think of the 2nd meaning as related to the first...the room is 3 meters if you were to walk across its length. A more abstract meaning is to convey or transmit understanding to somebody: "How can I get this idea across to you?" Again, the meaning is related, although we are no longer talking about physical distance, but rather traversing the understanding between two people. Does that make sense?