before in WordNet English dictionary

1. at or in the front
   "I see the lights of a town ahead"; "the road ahead is foggy"; "staring straight ahead"; "we couldn't see over the heads of the people in front"; "with the cross of Jesus marching on before"
   ahead  in front  before  ahead  in front  before 
   
2. earlier in time; previously
   "I had known her before"; "as I said before"; "he called me the day before but your call had come even earlier"; "her parents had died four years earlier"; "I mentioned that problem earlier"
   earlier  before  earlier  before