 The phrase “in a prior and a posterior sense” seems to have been derived from Arabic philosophy. H.A. Wolfson has presented evidence for Aristotle’s recognition of a type of term intermediate between equivocal and univocal terms, some instances of which were characterized by their use according to priority and posteriority. He showed that Alexander of Aphrodisias called this type of term ‘ambiguous’ and that the Arabic philosophers, starting with Alfarabi, made being said in a prior and a posterior sense the main characteristic of all ambiguous terms. So far as the medieval Latin west is concerned, the main sources for the notion of an ambiguous term said in a prior and a posterior sense are Algazel and Avicenna, both of whom became known in the second half of the twelfth century, and both of whom used the notion to explain uses of the word ‘being’.