The story
- Vulgar Latin · derived from*b(e)rillāre
- English todaybrillo pad
From a trademark, probably related to brilliant. The company has claimed that the name derives from a Latin word for bright, but there is no such fitting word in attested Latin; the ancestor of such verbs as Italian brillare (“to shine”) would be a hypothetical Vulgar Latin *b(e)rillāre.
Etymology from Wiktionary, CC BY-SA 4.0.