The word is attested only once in A-N, and appears in TLL without further context (as one of the glosses in John of Garland’s Latin Unus Omnium). The DMLBS lists nautabilis, and translates ‘that can be crossed, carried, or sim. by boat’ (1893a), parallel to the verb nautare (1893a): ‘to travel by boat’ or ‘to carry by boat’. It provides only one attestation, which is the same Unus Omnium excerpt, also taken from the TLL edition. In addition, the DMLBS also lists natabilis (1887b), glossed as ‘of or pertaining to swimming’. DMF, TL and Gdf demonstrate that both the above senses are attested in French for noable, so without any further context readily available (the full Latin text remains unpublished), it is impossible to determine which one is relevant here.