(les) pantalons.
The word "trousers" in French is spelled "pantalon."
"Les trousers" is masculine in French. The word for "trousers" in French is "le pantalon," which is a masculine noun.
Trousers = un pantalon
Pantaloons
pantalon is a French word. It means 'trousers'.
le pantalon
a pair of trousers
In French, the word for trousers is "pantalon," which is singular. However, when referring to trousers as a pair, it is often treated as plural, as in "des pantalons." So, while "pantalon" is singular, the term for trousers is commonly used in the plural form in everyday language.
pantalon d'école
un pantalon noir
des pantalons rouges
If you mean trousers it's - un pantalon