In Romanian, just like in English, some nouns have a "defective number." This means they exist only in the singular form (singularia tantum) or only in the plural form (pluralia tantum).
Singular-Only Nouns (Singularia Tantum)
Nouns that refer to materials, substances, and abstract concepts generally do not have a plural form. In fashion, words for fabrics like wool, velvet, linen, and lace are always singular. The same applies to abstract qualities like elegance and luxury.
Notice that when you combine two singular-only nouns with și (and), they form a compound subject and take a plural verb, but the nouns themselves remain strictly in their singular forms.
Plural-Only Nouns (Pluralia Tantum)
On the flip side, some words only ever exist in the plural. This typically includes items made of two parts or certain mass and collective concepts. Even if you are talking about a single conceptual item or event, you must use plural verbs, plural adjectives, and plural articles.
Common examples you will encounter include ochelari (glasses), bretele (suspenders), zori (dawn), cosmetice (cosmetics), and aplauze (applause).
