Definition of ortho- in English:


Pronunciation: /ˈɔːθəʊ/

combining form

  • 1Straight; rectangular; upright: orthodontics
  • 1.1Right; correct: orthoepy
  • 2 Chemistry Denoting substitution at two adjacent carbon atoms in a benzene ring, e.g. in 1,2 positions: orthodichlorobenzene Compare with meta- and para-1.
  • 3 Chemistry Denoting a compound from which a meta-compound is formed by dehydration: orthophosphoric acid


from Greek orthos 'straight, right'.

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Word of the day milord
Pronunciation: məˈlôrd
used to address an English nobleman