Definitions:
a small room in which a prisoner is locked up or in which a monk or nun sleeps

the smallest structural and functional unit of an organism, which is typically microscopic and consists of cytoplasm and a nucleus enclosed in a membrane.

a small group forming a nucleus of political activity, typically a secret, subversive one

a device containing electrodes immersed in an electrolyte, used for generating current or for electrolysis.

the local area covered by one of the short-range transmitters in a cellular telephone system.