Derivational etymology deriving the verb from a verb with a similar meaning (but not identical: to shout is not to speak). It does not imply any formal change. Orion's text is probably faulty: the explanation is about βάζω and its assumed derivative βράζω, and in the wording ὡς φῶ φάζω, καὶ πλεονασμῷ τοῦ ρ φράζω the καὶ πλεονασμῷ τοῦ ρ does not apply to the etymology of φράζω, for which Philoxenus had a different explanation (see φράζω / προΐημι), but to the derivation of βράζω out of βάζω. The later sources deriving from Orion don't have this explanation of φράζω as derived from *φάζω: they provide the parallel *φῶ, *φάζω as *βῶ, βάζω, and stop there. The derivation of βράζω by addition of [r] was found at the end of Orion's original notice: this state is preserved in the Genuinum, but the abbreviator of Orion made a confusion and applied the "addition of [r]" to the preceding φάζω, hence φράζω—maybe because he was more familiar with φράζω than with βράζω.