narrow down

narrow down (http://definr.com/narrow down)

     v 1: define clearly; "I cannot narrow down the rules for this
          game" [syn: pin down, peg down, nail down, narrow,
           specify]
     2: define clearly; "Can you pin down the difficulties" [syn: {pin
        down}]
     3: become more special; "We specialize in dried flowers" [syn:
        specialize, specialise, narrow] [ant: diversify, diversify]