Regex expression to find specific words within the subject line or body of email (content) regardless of case and plurals

Hello..

I have been working on a regex expression that would do word matches against the verbiage in the subject line and the body of an email for the purpose of deleting these emails.

A portion of the expression I have been using so far is:

\b\w*(companionship|handsome|relationship|refinance|gutter|cleanse|dating|pain|knee|joint|pain||hemorrhoid|hemorrhoids|diabetes)\w*\b

There are two things that I have not been able to figure out is how to do.

- Make the match of words be case insensitive for all of the words in the list

- How to deal with plurals, such as hemorrhoid/hemorrhoids.

Are there additional regex parameters that will do either of those things when added to the expression?

My thanks for your help!

Paul