Secessionists rhymes with:
impressionists, abortionists, constitutionists, extortionists, impressionists, isolationists, nutritionists, preservationists, protectionists, receptionists, rejectionists, reservationists, revolutionists, segregationists
Secessionists sounds like:
schenectady's, semi-heights, sense-datas, sensitize, shamanists, smokestack, smokestacks, sunsets, sunstates, sunsweet's, swimsuits