formal — being in accordance with the usual requirements, customs, etc.; conventional: to pay one's formal respects.
normal — conforming to the standard or the common type; usual; not abnormal; regular; natural.
Three-syllable rhymes
informal — without formality or ceremony; casual: an informal visit.
Four-or-more syllable rhymes
paranormal — of or relating to the claimed occurrence of an event or perception without scientific explanation, as psychokinesis, extrasensory perception, or other purportedly supernatural phenomena.
