Even though the term is defined by the text in its single attestation, its meaning remains unclear. The editors of Alchimie suggest that teule is an unusual spelling of an aphetic form of esteille, and their definition is given here. Alternative interpretations are, hypothetically, ‘sea-worn brick’ (cf. tieule) or ‘coral’ (cf. teile¹). There is, however, no further support for either of these interpretations.