1

1 (http://definr.com/1)

     adj : used of a single unit or thing; not two or more; "`ane' is
           Scottish" [syn: one, i, ane]
     n : the smallest whole number or a numeral representing this
         number; "he has the one but will need a two and three to
         go with it"; "they had lunch at one" [syn: one, I, ace,
          single, unity]