σημεῖον
sēmeion

Διχῶς δὲ λέγεται ζῴδιον, καθ’ ἕνα μὲν τρόπον τὸ ιβʹον μέρος τοῦ ζῳδιακοῦ κύκλου, ὅ ἐστι διάστημά τι τόπου ἢ ἄστροις ἢ σημείοις ἀφοριζόμενον, καθ’ ἕτερον δὲ τὸ ἐκ τῶν ἀστέρων εἰδωλοπεποιημένον κατὰ τὴν ὁμοιότητα καὶ τὴν θέσιν τῶν ἀστέρῶν.

‘The word “zōidion” is uttered in two ways, according to one way as the 12th part of the zodiac, which is some interval of space marked off by either stars or points, and according to the other as the image formed from the stars according to the likeness and the position of the stars.’

(...) ἔστι γὰρ ἐνιαύσιος χρόνος, ἐν ᾧ ὁ ἥλιος περιπορεύεται τὸν ζῳδιακὸν κύκλον καὶ ἀπὸ τοῦ αὐτοῦ σημείου ἐπὶ τὸ αὐτὸ σημεῖον ἀποκαθίσταται.

‘(...) for it is the time of a year, in which the sun goes around the zodiac and is returned from the same point to the same point.’

Ἀρκτικὸς μὲν οὖν ἐστι κύκλος ὁ μέγιστος τῶν ἀεὶ θεωρουμένων κύκλων, ὁ ἐφαπτόμενος τοῦ ὁρίζοντος καθ’ ἓν σημεῖον καὶ ὅλος ὑπὲρ γῆν ἀπολαμβανόμενος, ἐν ᾧ τὰ κείμενα τῶν ἄστρων οὔτε δύσιν οὔτε ἀνατολὴν ποιεῖται, ἀλλὰ δι’ ὅλης τῆς νυκτὸς περὶ τὸν πόλον στρεφόμενα θεωρεῖται.

‘The arctic circle is the biggest of the always visible circles, the one touching the horizon in one point and as a whole taken aside above the earth, in which the stars lying in it never perform a setting nor a rising, but are observed during the whole night turning around the pole.’