The nominative singular of the headword is attested only here, but other forms occur, e.g., in Apollonius Rhodius, Argonautica 3.1266 (accusative singular). The commonest form is the neuter plural θαμινά , used adverbially (example at sigma 974); cf. Erotianus theta2; Hesychius theta82, theta83; Synagoge theta11; Photius theta18; Lexicon Ambrosianum 2; and here in the Suda theta 34, theta 35, theta 36, theta 37.
[1] Both this word and its gloss could also be translated as 'very crowded' and and 'very packed' respectively. Neither this (nominative singular masculine) nor any other form of the superlative of θαμινός is attested elsewhere, apart from Lexicon Ambrosianum 18.