Although not found in the French or Latin dictionaries, the OED (with an earliest attestation dated to c.1503) and the MED (tentatively dated to c.1300) both suggest that the word must be a rare synonym for oste¹, osteler¹ and ostelein. As such, it may be considered an abbreviated form of osteler¹, in the same way as osterie is of ostelerie. Alternatively – and without further context – the word may also be interpreted as a variant of the formally similar but semantically unrelated ostoir¹, which is equally rare (and just as problematic to gloss).