I'm a bit lost on what a morpheme is. The "ceive" in "conceive" is surely related to "perceive" and "deceive",(reply>), The problem being, you can't just add "ceive" to existing words and suddenly they have a different meaning. Ceive in itself also has no meaning in English. Unlike "un", which has a meaning of "not, negative, inverse of" when applied to words, or "like", which by itself has a meaning.