This plural headword is first attested in a figurative usage in Herodotus 9.9.2: if the Athenians side with Persia against Sparta in 480, this will open great klisia/des into the Peloponnese.
Moeris' Attic Lexicon defines klisia/des as "two-door gates in Attic"; the term is defined as "double gates" in Hesychius kappa3013, and with the definition given by the Suda in Photius (kappa792 Theodoridis).
[1] For 'or tents', cf. generally kappa 1811.