Well I used denims when I posted my thread about high heels, but it's not the word I normally use, I just say jeans. However jeans now come in all materials and the name has become generic for a cut or style rather than the material they're made of, like cord jeans, sailcloth jeans etc.
So I used the name of the cloth from which they were originally made; denim, which I believe started out as cloth de Nimes, named for the town in France where it originated.
Giok