Found:

Pluralia tantum

MORPHOLOGY: a traditional term used for words which (a) end in a plural affix, (b) have a plural meaning, and (c) do not have a singular counterpart. EXAMPLE: in Dutch plural nouns can be formed by adding the suffix -en (hond-honden 'dog(s)'). But some nouns such as hersenen 'brains', annalen 'annals' and watten 'cotton wadding' have a plural meaning, end in the plural affix -en, and have no singular counterpart (*hersen, *annaal, *wat).

LIT.	Scalise, S. (1984)