τροπικός

τὸ δὲ τάχιον αὐτὸν διαδεχθῆναι παρεσκεύασαν ὁ Ἄρης καὶ ὡροσκόπος καὶ ἡ Σελήνη ἐν τροπικῷ ζῳδίῳ καὶ ὀλιγαναφόροις τετυχηκότες

‘The fact that he was succeeded quickly was provided by Mars and the Ascendant and the Moon, which were in a tropical zodiac sign and ones of short rising time.’

related to a turn (τροπή), in particular a solstice

Μετὰ μέντοι γε τὴν θερινὴν τροπὴν οὐκέτι πρὸς τὰς ἄρκτους παροδεύων ὁ ἥλιος θεωρεῖται, ἀλλ’ ἐπὶ τὰ ἕτερα μέρη τρέπεται τοῦ κόσμου, διὸ καὶ κέκληται τροπικός.

‘Since after the summer solstice though the sun is no longer observed travelling to the north, but it turns itself to the other parts of the cosmos, for this reason it (i.e., the summer tropic) has been named “tropical” too.’