ἰσόκοιλος
From LSJ
μὴ ἐν πολλοῖς ὀλίγα λέγε, ἀλλ΄ ἐν ὀλίγοις πολλά → don't say little in many words, but much in a few words (Stobaeus quoting Pythagoras)
English (LSJ)
ον,
A with equal cavities, αὐλός Plu.2.1021a, Theo Sm.p.60 H.(pl.).
German (Pape)
[Seite 1264] gleich hohl, αὐλός Plut. de an. procr. e Tim. 12.