n. The act of cleaving or splitting, or the state of being cloven.n. In mineralogy, the property possessed by many crystallized minerals of breaking readily in one or more directions, by which means surfaces more or less smooth are obtained.n. In geology, the property possessed by certain rocks of being easily split or divided into thin layers.n. In embryology, segmentation, specifically of the vitellus: distinctively called egg-cleavage or yolk-cleavage. See segmentation.