In Palindrian, perfect words are distinguished from imperfect words: the former are the odd-numbered palindromes; the latter are the even-numbered palindromes. The reason for this distinction lies in the fact that odd-numbered palindromes consist of two palindromic words, joined by a "keystone," which may be a consonant or a vowel, which is therefore not part of the two palindromic words, but intervenes from the outside to determine the union of the two words. The imperfect words are composed of two elements which, however, stand together without a perfect union, but are simply juxtaposed to each other. Their union is unstable, since there is no external element that intervenes to end their mutual difference and opposition.
mugum (city) is perfect, because the two parts mu- and -um are held together by a third element, which resolves their opposition, thus enabling the harmony of the opposite terms.
möllöm (to live), on the other hand, is imperfect, because it is composed of the two elements möl- and -löm, without an external element that intervenes to ensure their union.