Plutarch, Life of Cicero 1.3-5
ὁ μέντοι πρῶτος ἐκ τοῦ γένους Κικέρων ἐπονομασθεὶς ἄξιος λόγου δοκεῖ γενέσθαι διὸ τὴν ἐπίκλησιν οὐκ ἀπέρριψαν οἱ μετ’ αὐτόν, ἀλλ’ ἠσπάσαντο, καίπερ ὑπὸ πολλῶν χλευαζομένην. κίκερ γὰρ οἱ Λατῖνοι τὸν ἐρέβινθον καλοῦσι, κἀκεῖνος ἐν τῷ πέρατι τῆς ῥινὸς διαστολὴν ὡς ἔοικεν ἀμβλεῖαν εἶχεν ὥσπερ ἐρεβίνθου διαφυήν, ἀφ’ ἧς ἐκτήσατο τὴν ἐπωνυμίαν. αὐτός γε μὴν Κικέρων, ὑπὲρ οὗ τάδε γέγραπται, τῶν φίλων αὐτὸν οἰομένων δεῖν, ὅτε πρῶτον ἀρχὴν μετῄει καὶ πολιτείας ἥπτετο, φυγεῖν τοὔνομα καὶ μεταθέσθαι, λέγεται νεανιευσάμενος εἰπεῖν, ὡς ἀγωνιεῖται τὸν Κικέρωνα τῶν Σκαύρων καὶ τῶν Κάτλων ἐνδοξότερον ἀποδεῖξαι.
The first member of the family who had the nickname ‘Cicero’ seems to have been worthy of note, because his descendants did not cast off the nickname, but were fond of it, even though it was ridiculed by many people. For Latin speakers call the chickpea ‘cicer’, and that ancestor, it seems, had a slight notch in the end of his nose, like the cleft in a chickpea, so from this he acquired the nickname. And when Cicero (the one about whom I am writing this biography) first began his public life and took up public office, his friends thought that he ought to drop or change his name, but he is said to have said, with youthful high spirits, that he would strive to make the name Cicero more renowned than Scaurus [‘Bulging-ankles’] and Catulus [‘Puppy’].