Forsooth Speech
As in "to speak forsoothly".
To speak in a period manner or style. Most SCAdians speak in a formalized type of modern English. Period English is very difficult to recognize.
-- Mistress Arlys o Gordon
In addition to the SCA usage of the term, we should perhaps keep in mind that the etymology of the word "forsooth" comes from the phrase "for truth". I take this to mean that we should speak honestly, letting no word of a lie or hint of dishonour cross our lips, an especially salient concept in a close-knit (read insular) and talkative (read gossipy) bunch of people like the SCA.
-- *Briana*