or  ortho-  comb form 1  :  hydrated or hydroxylated to the highest degree <orthophosphoric acid>   2  :  involving substitution at or characterized by or having the relationship of two neighboring positions in the benzene ring - abbr. o- <ortho-xylene or o-xylene>  - compare META-2 PARA-2   .
 
 
 
Similar sounding terms:   ortho 
 
Published under license with Merriam-Webster, Incorporated.  © 1997-2024.