Conditional formatting across sheets

[Lindsey540]

Hi! I'm trying to persuade excel in Office 365 to do some conditional formatting using two sheets but struggling to find out how. I'd be grateful for any advice!

I have 2 sets of sheets, A,B,C and X,Y,Z,  All of the sheets contain lists of words; sheets A, B and C have additional columns with numerical data in. 

I want excel to check the list of the words in sheet A against those in sheet X: where  a word from sheet A appears on sheet X (anywhere on the list), I'd like it to put an X in next to the word in sheet A, in a new column. Then I need to set it to go through the same process for sheets Y and Z. Then I need to check sheets B and C in the same way. 

It seems like it should be possible - but I just don't know how!!

Thanks in advance!

[#2]

@Lindsey540 

It's hard to get an accurate picture (at least, to be sure it's accurate) from just a verbal description. Remember the old saw about a picture being worth....

So would it be possible for you to upload and post a representative sample of what you're trying to describe? The actual (rather than just an image) would save us from guessing and from having to re-create.

I'm sure there'll be many who'll be happy to help.