Illustrated Glossary of Organic Chemistry

Anti-Markovnikov addition: In an addition reaction of a generic electrophile HX to an alkene or alkyne, the hydrogen atom of HX becomes bonded to the carbon atom that had the least number of hydrogen atoms in the starting alkene or alkyne. The 'anti' in 'anti-Markovnikov' refers to the fact the reaction does not follow Markovnikov's rule, instead of being a reference to anti addition stereochemistry.

Anti-Markovnikov addition of hydrogen bromide to propene, illustrating the peroxide effect.

Markovnikov addition of hydrogen bromide to propene.