Apologies, it's 'diplopia' (no S), which I guessed was something about 'two', but having looked it up, it's nothing to do with a diplodocus. It's 'double vision', FFS. I assume Self never ever would use the common name of flowers in his garden, but only the Latin names, because only plebs would refer to things like roses, daisies, and marigolds using the words 99.99% of the population would use (even academic botanists, if they were talking to ordinary gardeners about gardening).
If you're a poet, or a novelist, go ahead, sure, use whatever fancy words you want (if you don't mind people interrupting the flow of reading so that they can look up words in the dictionary), but if you want people to easily understand what you are saying, even if they are tricky subjects (or, maybe, *especially* if they are tricky subjects), use the simplest language that accurately conveys your meaning.
Don't be like Will. Say 'double vision', not 'diplopia'.