Cleave means to adhere, cling or remain faithful.
Cleave is a verb.
Synonyms: be constant, stick, uphold, hold fast.
Antonyms: abandon, separate, come loose, forsake, let go,release.
Note: Note that cleave can have two opposite meanings i.e., to cling or to split. When used to indicate adherence, cleave is usually followed by the word "to."
The workers were unable to cleave the unusually hard stone.
The carpenter spent most of the morning cleaving the wood.
Frightened students cleave to their teachers.