The electrons involved in the formation of a covalent bond are

These electrons are "bonding pairs."

Explanation:

Two atoms share a pair of two valence electrons between them to form a covalent bond. (Of course they can share more than one pairs to produce a double, or a triple bond.) These valence electrons are called "bonding pairs."

In contrast, if a pair of valence electrons on an atom are not shared with another atom, that pair of valence electrons is called a "lone pair".