I think you’re probably having no trouble absorbing the meaning of this word, but just in case, here’s a little breakdown to help it stick better while waiting for the mods to reply:
除=‘to get rid of’; 外=‘outside’
When something is rejected and put outside, you get ‘exclusion’, and hence, a possible ‘exception’ (to the set in which it would otherwise be included).
Sure, we’ll add this one soon. But as @Leebo mentioned, if you have further content suggestions, a faster way to get our attention is either our email or live chat! (Thanks for the tag, @TheFlaminMunch )