Definition of "dialectic"

Is it [prodezza] a mere dialectic variation of prudenza, […]?

1813, W[illiam] Taylor, Jun[ior] of Norwich, English Synonyms Discriminated, London: W. Pople, page 51

[…] if any one has, in common discourse, an indistinct, hesitating, dialectic, or otherwise faulty, delivery, his Natural manner certainly is not what he should adopt in public speaking; […]

1828, Richard Whately, Elements of Rhetoric. Comprising the Substance of the Article in the Encyclopædia Metropolitana: with Additions, &c., 2nd edition, Oxford: W. Baxter, for John Murray, London; and J. Parker, Oxford, page 351

But our able Secretary, Mr. Laidlay, has referred me to another alphabet, dialectic of the Hebrew, as set forth in the interpretation of the bilingual inscription of Thongga (Journal Asiatique, Fevrier, 1843) to which be conceives the characters of this brief specimen may be considered more properly to belong.

1850 January, Henry [Whitelock] Torrens, “Some conjectures on the progress of the Bráhminical Conquerors of India”, in Journal of the Asiatic Society of Bengal, volume XIX, number XXXVII, Calcutta: J. Thomas, Baptist Mission Press, published 1851, page 13

[…] we have a theory sufficiently consistent with the remote philological relations traceable between Cymri and Gael, and with the close dialectic affinities between Celtic Scotland and Ireland.

1863, Daniel Wilson, Prehistoric Annals of Scotland, 2nd edition, volume II, London, Cambridge: Macmillan and Co., page 185