From interstō.

• (Classical Latin) IPA^(key): [ɪnˈtɛr.stɛs]
• (modern Italianate Ecclesiastical) IPA^(key): [inˈtɛr.stes]

interstes (genitive interstitis); third-declension one-termination adjective

1. (Ecclesiastical Latin, hapax legomenon) standing between or among
   • 207 CE – 208 CE, Tertullianus, Adversus Marcionem 4.33:

     si desierunt vetera et coeperunt nova interstite Iohanne

     • Translation by Ernest Evans

       if old things have come to an end, and new things have begun, with John as the point of division

Third-declension one-termination adjective.

See the etymology of the corresponding lemma form.

interstēs

1. second-person singular present active subjunctive of interstō

• “interstes”, in Charlton T. Lewis and Charles Short (1879), A Latin Dictionary, Oxford: Clarendon Press
• "interstes", in Charles du Fresne du Cange, Glossarium Mediæ et Infimæ Latinitatis (augmented edition with additions by D. P. Carpenterius, Adelungius and others, edited by Léopold Favre, 1883–1887)
• “interstes”, in Gaffiot, Félix (1934), Dictionnaire illustré latin-français, Hachette.