disputant

väittelijä A participant in a dispute.
1893, w:Henry James|Henry James, Collaboration http://www.henryjames.org.uk/collab/CLtext.htm

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.

(rfquotek)