| Attribute | Value | Sp. example | Sp. tag |
| number | singular | el libro | sing |
| plural | los libros | plu | |
A special case concerning number is those nouns with the same morphological form for the singular and the plural:
`la crisis', `la dosis', `el martes', `el chasis', `el análisis'
`las crisis', `las dosis', `los martes', `los chasis', `los análisis'
Just as in the case of `el/la responsable' above, we leave these nouns unvalued for Number. We obtain the value via unification with the value of the article and/or adjective accompanying the noun. Again, we could add a language-specific value to mark these nouns.
Another special case is that known as pluralia tantum. This group comparises nouns which are always plural, where the plurality does not come from any inflectional process but is rather inherent to the noun itself:
`víveres', `añicos', `entendederas', ...