I can actually answer this question. Back in the day I was going through Oxford Dictionary and it mentioned that all the meaning use words from a like of about 3,000 words. The list, IIRC, was also at the back of the dictionary. And it also mentioned that on rare occasions they have to use words outside of those 3,000.
Source: My memory of something I read at British Council Library 17 years ago.
Source: My memory of something I read at British Council Library 17 years ago.