Merriam-Webster's Collegiate® Dictionary, 11th Edition
ACROSS
I. adverb
Etymology: Middle English acros, from Anglo-French an crois, from an in (from Latin in) + crois cross, from Latin crux
Date: 14th century
in a position reaching from one side to the other ; crosswise , to or on the opposite side, so as to be understandable, acceptable, or successful ,
II. preposition
Date: 1591
1. from one side to the opposite side of ; over , through , on the opposite side of , so as to intersect or pass through at an angle , so as to find or meet ,
4. throughout , so as to include or take into consideration all classes or categories ,
III. adjective
Date: 1621
being in a crossed position