chairbacker noun an unordained, self-taught preacher US,1955
— Frederic G. Cassidy, DictionaryofAmericanRegionalEnglish, p. 584, 1985
“Chairbacker” (a preacher whose pulpit was a common chair in a slave cabin) and “floor preacher” became common appellations[.] — Mechal Sobel, Trabelin’On, p. 160, 1988