Typing each synonym in one search box when using the advanced search page, then adding OR in between each synonym - then don't put anything else in that box. (See screenshots below)

Example:  Instead of searching for:

women AND images AND media

try

(women OR females) AND images AND media  <--If you didn't have multiple search boxes, you'd have to do it this way for it to work

• This tells the database that you’ll take results with one keyword OR the other.
• You’ll take either result, you’ll take both if they’re available.
• This expands your search and broadens your search results.

How this looks in the RamSearch advanced search interface:

Same thing on mobile: