A hemiaminal is a functional group or type of chemical compound that has a hydroxyl group and a amine attached to the same carbon atom: -C(OH)(NR2)-. R can be hydrogen or an alkyl group.
An aminal or aminoacetal is a functional group or type of chemical compound that has two amine groups attached to the same carbon atom: -C(NR2)(NR2)-. Again R can be hydrogen or a alkyl group.
The aminal and the hemiaminal groups are the cousins of hemiacetals and acetals with nitrogen replaced by oxygen. Aminals and hemiaminals are encountered in for instance the Fischer indole synthesis, the chemistry of imines or the synthesis of Carbazol-9-yl-methanol.