ἤϊσαν

From LSJ

Περὶ τοῦ ἐπέκεινα τοῦ νοῦ κατὰ μὲν νόησιν πολλὰ λέγεται, θεωρεῖται δὲ ἀνοησίᾳ κρείττονι νοήσεως → On the subject of that which is beyond intellect, many statements are made on the basis of intellection, but it may be immediately cognised only by means of a non-intellection superior to intellection

Porphyry, Sententiae, 25

French (Bailly abrégé)

3ᵉ pl. impf. épq. et ion. de εἶμι.

Russian (Dvoretsky)

ἤϊσαν: эп.-ион. (= ᾖεσαν) 3 л. pl. impf. к εἶμι.