[1] : WordNet (r) 2.0

zero in
     v 1: direct onto a point or target, especially by automatic
          navigational aids syn: range in, home in
     2: adjust as by firing under test conditions the zero of a
        gun; "he zeroed in his rifle at 200 yards" syn: zero
see also:
range in home in zero 

Zero >> Z Words
Zero, definition of term: Zero
zero_pag1.html

Zero In >> Z Words
Zero In, definition of term: Zero In
zero+in_pag1.html

Zero Hour >> Z Words
Zero Hour, definition of term: Zero Hour
zero+hour_pag1.html

Absolute Zero >> A Words
Absolute Zero, definition of term: Absolute Zero
absolute+zero_pag1.html