δημήγορος or δημηγόρος; → δημηγόρος (αρχαία)

[spiros]

δημήγορος or δημηγόρος;

Woodhouse appears to favour δημήγορος.
https://lsj.gr/wiki/demagogue
https://lsj.gr/wiki/%CE%B4%CE%B7%CE%BC%CE%B7%CE%B3%CF%8C%CF%81%CE%BF%CF%82

[billberg23]

There are 46 instances of δημηγόρος (not counting oblique cases) in both classical and non-classical authors, but only 3 late/Byzantine texts show δημήγορος, which is apparently a mistake based on analogy with such nouns as συνήγορος, κατήγορος, etc., e.g.Theognostus Gramm., Canones sive De orthographia 541.3:
Τὰ παρὰ τὸ ἀγορῶ συγκείμενα τὴν μὲν παραλήγουσαν διὰ τοῦ ο μικροῦ, τὴν δὲ τρίτην ἀπὸ τέλους ἔχει διὰ τοῦ η· οἷον, συνήγορος· κατήγορος· θεήγορος· δημήγορος.

[spiros]

Interesting, so it could not be an adjectival form either as a synonym to "δημηγορικός", i.e. στροφαὶ δημήγοροι?

https://lsj.gr/wiki/%CE%B4%CE%B7%CE%BC%CE%B7%CE%B3%CF%8C%CF%81%CE%BF%CF%82
https://lsj.gr/wiki/demagogic
https://lsj.gr/wiki/rhetorical
https://lsj.gr/wiki/oratorical