Latin: 'and not' (of); 'nor' (of), used to distinguish from a homonym. For example: Cheilosia antiqua Becker, 1894 nec (Meigen, 1822) indicates that the taxon described by Becker (1894) as antiqua Meigen, 1822 is not the same taxon as Meigen (1822) himself described under the name antiqua.