orth-
See ortho-.
* * *
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)
Medical dictionary.
2011.