Derivational etymology. Apparently ἀΐσσω was chosen as the etymon because it has the hiatus that is missing in the other etymologies. From the semantic point of view, ἀΐσσω is assumed to be an equivalent of "to go" and the etymology is similar to. the usual one by εἶμι (see ἤϊα / εἶμι). Alternatively, the etymology may have been designed for the meaning "chaff" of ἤϊα, since the chaff indeed leaps when the grain is winnowed (see (ἤϊα / ἵημι). And from there it would have been extended to the general meaning "provisions for a journey", implying that "to leap" means "to go"