The 2C-X Chemical Family is a group of psychedelic phenethylamines that share the same basic 2C structure. The name '2C' is an acronym for the two carbons between the benzene ring and the amino group in all 2C chemicals. There are also two methoxy groups on the the 2 and 5 positions of the benzene ring. The -x denotes a number of different varieties of 2C's that differ in their substituents on the 3 and 4 positions of the benzene ring.
Alexander Shulgin coined this term and also synthesized the majority of the 2C's, publishing detailed information about their synthesis in his book PiHKAL (Phenethylamines i Have Known And Loved).