The origin of pleonastic that can be traced back to Old English where it could appear in syntactic constructions consisting of a preposition + demonstrative pronoun (i.e. for þy þat, for þæm þe) or a subordinator (i.e. oþ þat). Its diffusion with other subordinators is considered an early Middle English development as a result of the standardization of this item as the general subordinator in the period, which motivated its use as a pleonastic word in combination with all kinds of conjunctions (i.e. now that, gif that, when that, etc.) and prepositions (i.e. before that, save that, in that). Its use considerably increased in late Middle English, declining throughout the 17th century. The list of subordinating elements includes relativizers (i.e. this that), adverbial relatives (i.e. there that) and a number of subordinators (i.e. after, as, because, before, beside, for, if, since, sith, though, until, when, while, etc.).
The present paper pursues the following objectives: a) to analyse the use and distribution of pleonastic that in a corpus of early English medical writing (in the period 1375-1700); b) to classify the construction in terms of the two different varieties of medical texts, i.e. treatises and recipes; and c) to assess the decline of the construction with the different conjunctive words. The data used as sources of evidence come from The Corpus of Early English Medical Writing, i.e. Middle English Medical Texts (MEMT for the period 1375-1500) and Early Modern English Medical Texts (EMEMT for the period 1500-1700).