alum in WordNet English dictionary

1. a double sulphate of aluminum and potassium that is used as an astringent (among other things)
   alum 
   
2. a person who has received a degree from a school (high school or college or university)
   alumnus  alumna  alum  graduate  grad 
   
3. a white crystalline double sulfate of aluminum: the potassium double sulfate of aluminum
   alum  potassium alum  potash alum 
   
4. a white crystalline double sulfate of aluminum: the ammonium double sulfate of aluminum
   alum  ammonia alum  ammonium alum