Alpha carbon
Carbon can be found in the Alpha or Beta form.
An alpha (α) carbon is the first carbon to which a functional group (i.e. Alchol, Aldehyde, Ketones and carboxylic acids) is attached.
We can have more than 1 carbon in a structure which has a functional group attached to it and therefore we cal the second carbon with a functional group, a Beta Carbon.
Refrences
Stryer et al p. 337