Well, vocabulary that we all understand. The reason that it's hard to describe to someone you've never met is the same reason why it's hard (impossible, I would say) to learn Aikido from a book to any reasonable level. Could you learn to be an opera singer from a book? Probably not - but if you were already an opera singer you could probably get a fair amount of useful information from that book.
Well, why not try and describe it? There seems to be plenty of people on Aikiweb who have attended various Internal Strength seminars at this stage, notwithstanding their own training.
At best, you might find that concepts chime with other people's experiences and that will help clarify one's own understanding. At worst, well, nobody will know what you're talking about, so no harm done
Aikiweb is a discussion forum, after all.