WordWeb Online

1. Encouraging, approving or pleasing
   "a favourable reply"; "he received a favourable rating"; "listened with a favourable ear"; "made a favourable impression";
   - favorable [US]
    
2. (of winds or weather) tending to promote or facilitate
   "the days were fair and the winds were favourable";
   - favorable [US]
    
3. Giving an advantage
   - advantageous, favorable [US]
    
4. Presaging or likely to bring good luck or a good outcome
   "a favourable time to ask for a raise";
   - golden, favorable [US], lucky, prosperous

See also: affirmative, affirmatory, approbative, approbatory, approving, beneficial, complimentary, discriminatory, expedient, following, good, indulgent, opportune, plausive, plus, positive, preferential, profitable, propitious

Antonym: disadvantageous