Not everyone is well-versed in how new clothing items are called, for example. Even fairly simple stuff like 'trousers' WILL be called 'pants' and you'll have to work around that - or else lose sales.
That's where synonyms come in. Make sure you think of every possible way your catalog items might be called. Keep tabs
on what your users search for if you must. But don't return the infuriating 'no results' page' because you didn't think of adding 'bikini' as a synonym for 'beachwear'.