Source : Free On-Line Dictionary of Computing

DIM statement
     
         (From "dimension") A {keyword} in most versions
        of the {BASIC} programming language that declares the size of
        an {array}.  E.g.
     
        	DIM A(100)
     
        declares a one-dimensional array with 101 numeric elements
        (including A(0)).
     
        {Visual Basic} uses the DIM (or "Dim") statement for any
        variable declaration, even {scalars}, e.g.
     
        Dim DepartmentNumber As Integer
     
        which declares a single (scalar) variable of type Integer.
     
        (1999-03-26)