sooner in WordNet English dictionary

1. comparatives of `soon' or `early'
   "Come a little sooner, if you can"; "came earlier than I expected"
   sooner  earlier  sooner  earlier 
   
2. more readily or willingly
   "clean it well, preferably with warm water"; "I'd rather be in Philadelphia"; "I'd sooner die than give up"
   preferably  sooner  rather  preferably  sooner  rather 
   

sooner in English Wiktionary