Originally Posted by
Hyoi
I would translate the jargon as "the -t ending on adverbs doesn't have any actual meaning that linguists know of, so they assume it is there because some of the forms without it ('amids', 'amongs', etc) violated some habit or preference in the language-making part of English speakers in the 1500s, and once the '-st' form was established for some adverbs, it spread to others because people's brains want adverbs to sound adverby"
As there isn't much evidence to work with any explanation will be speculative, but I would put forth for consideration several facts:
-1: This seems to happen when the historical word is an preposition that was turned into an adverb by adding the genitive case suffix -s.
-2: Modern English doesn't retain case endings, but sometimes they are still around as baked-in parts of modern English words (consider for example amidships, and ponder why it isn't amidshipst).
-3: The word abreast looks like it follows the pattern but it doesn't, it derives from an + brest "on breast (i.e. side-by-side)".
-4: the seemingly meaningless addition of a word-final dental to a word that didn't historically have one also happens in some German words (e.g. axe/Axt, moon/Mond)
-5: The word against is unusual in that the -st version is the only acceptable one in most English dialects, except some like Scottish that never adopted it.
So the most interesting conclusion I have drawn is that when depicting Scottish or derivative accents in text form, "I nae be standin' again ye" is more correct than "I nae be standin' again' ye". (quick, somebody do an analysis of apostrophe placement in Durkon's speech so I can get back to serious linguistics in the real world :D)