Hydrogen Abstraction Definition:

In radical reactions, a type of arrow-pushing pattern I which a hydrogen atom is abstracted by a radical, generating a new radical.

Hydrogen Abstraction Explained:

Abstraction is the removal of an atom or a molecule by radicals, in this case, Hydrogen. The rates and selections of the hydrogen-atom abstraction reactions of electrically-neutral free radicals are known to depend on polar effects that operate in the transition state. Thus, an electrophilic species such as an alkoxyl radical abstracts hydrogen much more readily from an electron-rich C–H bond than from an electron-deficient one of similar strength.