What is the X in X-mas?
suffix forming nouns of action, state, condition, doctrine, from French -isme or directly from Latin -isma, -ismus, from Greek -isma, from stem of verbs in -izein. Used as an independent word, chiefly disparagingly, from 1670s.
Action, process; practice: vegetarianism.
Characteristic behavior or quality: puerilism.
State; condition; quality: senilism.
State or condition resulting from an excess of something specified: strychninism.
Doctrine; theory; system of principles: Darwinism.