Noun
(meteorology) A cloud species which shows vertical formations giving a crenellated appearance, associated with cirrus, cirrocumulus, altocumulus, and stratocumulus genera.
Alternative form of castellan
Source: en.wiktionary.orgIt is occasionally seen with cirrocumulus and altocumulus of the species stratiformis, castellanus, and floccus, and with stratocumulus of the species stratiformis and castellanus. Source: Internet