one in WordNet English dictionary

1. the smallest whole number or a numeral representing this number
   "he has the one but will need a two and three to go with it"; "they had lunch at one"
   one  1  I  ace  single  unity 
   
2. a single person or thing
   "he is the best one"; "this is the one I ordered"
   one 
   

1. used of a single unit or thing; not two or more
   "`ane' is Scottish"
   one  1  i  ane 
   
2. eminent beyond or above comparison
   "matchless beauty"; "the team's nonpareil center fielder"; "she's one girl in a million"; "the one and only Muhammad Ali"; "a peerless scholar"; "infamy unmatched in the Western world"; "wrote with unmatchable clarity"; "unrivaled mastery of her art"
   matchless  nonpareil  one  one and only  peerless  unmatched  unmatchable  unrivaled  unrivalled 
   
3. being a single entity made by combining separate components
   "three chemicals combining into one solution"
   one 
   
4. used informally as an intensifier
   "that is one fine dog"
   one 
   
5. indefinite in time or position
   "he will come one day"; "one place or another"
   one 
   
6. of the same kind or quality
   "two animals of one species"
   one 
   
7. having the indivisible character of a unit
   "a unitary action"; "spoke with one voice"
   one  unitary