There is an issue with how many words they can be expected to add to the list. For synonyms of underpants Wiktionary gives
boxer shorts, briefs, bloomers, (UK) pants, panties, (slang) butt-huggers, undies, (slang) tighty whities, knickers, drawers, (UK, Australia) smalls, (slang, UK) shreddies, (slang, New Zealand) gruds, longjohns, thong, underwear
But against this they have to put in the words that would cover what most people who have understood the word would say in English. It is quite clear from looking in a variety of dictionaries that there are four words much more common than all the others, so clearly these should be included. They are
- pants (UK)
- underpants (US)
- drawers (old-fashioned/regional)
So: yes, definitely.
Thank you for getting back to me. I added a reply on another similar post to say that in Scots (I live in Central Belt of Scotland) we say "drawers" - the main reason I added this was because many people who live in Scotland are learning Scots Gaelic. I'm aware you couldn't possible add them all.