[ra.tio.nal.ism] n (1827) 1: reliance on reason as the basis for establishment of religious truth
2. a: a theory that reason is in itself a source of knowledge superior to and independent of sense perceptions b: a view that reason and experience rather than the nonrational are the fundamental criteria in the solution of problems
3: functionalism -- ra.tio.nal.ist n -- rationalist or ra.tio.nal.is.tic adj -- ra.tio.nal.is.ti.cal.ly adv