narrow down

narrow down
    v 1: define clearly; "I cannot narrow down the rules for this
         game" [syn: {pin down}, {peg down}, {nail down}, {narrow
         down}, {narrow}, {specify}]
    2: become more focus on an area of activity or field of study;
       "She specializes in Near Eastern history" [syn: {specialize},
       {specialise}, {narrow}, {narrow down}] [ant: {branch out},
       {broaden}, {diversify}]