un, una, uns, unes

Use un with masculine singular nouns and una with feminine singular nouns: un carrer, una plaça. The plural forms are uns and unes. They commonly introduce some unspecified members of a set rather than a known group.

An indefinite article is not required before every Catalan noun. For an unspecified amount of a mass noun, say vull aigua; un cafè normally means one serving of coffee. A bare plural such as compro llibres can describe books in general or an unspecified quantity.

Unlike el and la, un and una do not elide before a vowel: un amic, una amiga. Their form follows the noun's grammatical gender, not the sound of its first letter.