ὁμαλόν
From LSJ
Ὁ κόσμος σκηνή, ὁ βίος πάροδος· ἦλθες, εἶδες, ἀπῆλθες → The world is a stage, life is your entrance: you came, you saw, you departed (Democritus fr. 115 D-K)
Russian (Dvoretsky)
ὁμᾰλόν: τό ровное место, равнина (ἐν τῷ ὁμαλῷ τὴν μάχην ποιεῖσθαι Thuc.).
Lexicon Thucydideum
planities, plain, flat country, 5.65.4, 5.65.6, 6.101.1, 6.101.3. 7.44.8.
planissimus, very flat, 4.31.2.