n 1 a  :  a unit of troy weight equal to ¹/₁₂ troy pound or 31.103 grams  b  :  a unit of avoirdupois weight equal to ¹/₁₆ avoirdupois pound or 28.350 grams  2  :  FLUID OUNCE .
 
 
 
Published under license with Merriam-Webster, Incorporated.  © 1997-2024.