Cage up is a phrase that means to confine someone or something in a small space. There are various synonyms for the phrase "cage up" including "enclose," "restrict," "imprison," "encircle," "confine," "trap," "shut in," "hem in," "box up," and "keep under lock and key." These words indicate the act of limiting someone's freedom and ability to move around. The phrase "cage up" is often used to describe the confinement of animals in zoos or cages, but it can also refer to the restriction of human rights or personal freedom. These synonyms help to convey different shades of meaning and can be used interchangeably depending on the context in which they are used.