Historical Events  Brands
Depends

Depend/depends

Everyone remembers this brand name as "Depends", yet when you see it today it is the singular "Depend".

Searching the internet throws up several references, and images, of the "remembered" name.

One explanation could be the phrase used in common language has become ingrained to such a level it is taken as the real name. For example, one would usually say "I am just going out to buy some Depends" even if the brand name is the singular "Depend". Repeating this often enough could lead to the word "Depends" being used in all circumstances, including remembering what the actual brand name is.