Syllogistic is the adjective from 'syllogism'. It has two everyday uses. The first is plain and technical: it simply means 'to do with syllogisms' — 'syllogistic reasoning', 'syllogistic logic', 'Aristotle's syllogistic form'. Here it is neutral, the vocabulary of a logic or philosophy class. The second use is a judgement, and it is the one that surprises learners: to call someone's thinking 'syllogistic' is often a gentle criticism. It suggests the argument marches from premise to premise in a stiff, mechanical way, arriving at a conclusion that is logically tidy but has lost touch with how complicated the real situation is. 'His syllogistic approach to the problem ignored the people involved.' You can usually tell which use is meant from what surrounds it: paired with 'logic', 'form' or 'reasoning' in an academic sentence it is neutral; paired with words like 'rigid', 'dry', 'mere' or set against 'real life' it is a complaint. There is also a noun use in philosophy — 'Aristotle's syllogistic' means his whole system of syllogisms — but that is specialist. The adverb is 'syllogistically'. It is a formal word; nobody says it at dinner.

三段論的、（用）三段論推理的。中性用法指「屬於三段論的」（三段論推理、三段論形式）；但也常帶貶意，形容一個人推論死板、照公式推、脫離現實，中文可說「硬套邏輯的」「推論很機械」。屬書面語、學術用語。