An apricot kernel is the apricot seed located within the fruit endocarp, which forms a hard shell around the seed called the pyrena (stone or pit).[1][2]
The kernel contains amygdalin, a poisonous compound, in concentrations that vary between cultivars. Together with the related synthetic compound laetrile, amygdalin has been marketed as an alternative cancer treatment. However, studies have found the compounds to be ineffective for treating cancer.[3]