Definition of "disputant"

One of the liveliest scenes of the performance was the evening, last winter, on which I became aware that one of my compatriots – an American, my good friend Alfred Bonus – was engaged in a controversy somewhat acrimonious, on a literary subject, with Herman Heidenmauer, the young composer who had been playing to us divinely a short time before and whom I thought of neither as a disputant nor as an Englishman.

1893, Henry James, Collaboration

[...] [T]here was found / Among the graveſt Rabbies diſputant / On points and queſtions fitting Moſes Chair, / Teaching not taught; [...]

1671, John Milton, “The Fourth Book”, in Paradise Regain’d. A Poem. In IV Books. To which is Added, Samson Agonistes, London: […] J. M[acock] for John Starkey […], page 89, lines 217–220