The problem of the nature and origin of the Macedonian language is still disputed by modern scholars, but does not seem to have been raised among the ancients.
We have a rare adverb "makedovisti" (important passages in Plutarch, Alex.51 and Eum.14), but the meaning of this form is ambiguous. The adverb cannot tell us whether Plutarch had in mind a language different from Greek (cf. "foivikisti", 'in Phoenician'), or a dialect (cf. "megaristi", 'in Megarian'), or a way of speaking (cf. "attikisti").
We have some 'Macedonian' glosses, particularly in Hesychius' lexicon, but they are mostly disputed and some were corrupted in the transmission. Thus "abroutes", 'eyebrows' probably must be read as "abrouFes" (with 't' which renders a digamma). If so, it is a Greek dialect; yet others (e.g. A.Meillet) see the dental as authentic and think that the word belongs to an Indo-European language different from Greek.
After more than a century we recognise among linguists two schools of thought.
For a long while Macedonian onomastics, which we know relatively well thanks to history, literary authors, and epigraphy, has played a considerable role in the discussion. In our view theGreek character of most names is obvious and it is difficult to think of a Hellenization due to wholesale borrowing. "Ptolemaios" is attested as early as Homer, "Ale3avdros" occurs next to Mycenaean feminine a-re-ka-sa-da-ra- ('Alexandra'), "Laagos", then "Lagos", matches the Cyprian 'Lawagos', etc.
The small minority of names which do not look Greek, like "Arridaios" or "Sabattaras", may be due to a substratum or adstatum influences (as elsewhere in Greece).
Macedonian may then be seen as a Greek dialect, characterised by its marginal position and by local pronunciations (like "Berevika" for "Ferevika", etc.).
Yet in contrast with earlier views which made of it an Aeolic dialect (O.Hoffmann compared Thessalian) we must by now think of a link with North-West Greek (Locrian, Aetolian, Phocidian,Epirote). This view is supported by the recent discovery at Pella of a curse tablet (4th cent. BC) which may well be the first 'Macedonian' text attested (provisional publication by E.Voutyras; cf. the Bulletin Epigraphique in Rev.Et.Grec.1994, no.413); the text includes an adverb "opoka" which is not Thessalian.
We must wait for new discoveries, but we may tentatively conclude that Macedonian is a dialect related to North-West Greek.
"Oxford Classical Dictionary," 3rd ed. (1996), pp.905,906