"PROCESS"
From Latin, "proceed," "advance."
Thomas hasn't been too happy with any "process" he's ever encountered, but that's just Thomas. When he got to Rainbow, "Rainbow Process" was already an established tradition. Realizing this "process" was the difference between "anarchy" and "chaos," Thomas made no attempt to alter, abolish, or manipulate it.
Webster's defines "process" as, "A system of operations in the production of something." Given that the Rainbow professes ideals of "Peace, Love, and Harmony," one might assume Rainbow process would concern itself with the production of those ideals. That's the kind of "process" Thomas could be happy with, but, he thinks, his experience shows,