all-nighter noun5 •(informal) Something that lasts throughout the whole night.That party was an all-nighter. •(informal) An instance of studying or working throughout the night without sleep. •(UK, slang) A session with a prostitute covering the entire night. •(US, slang) A criminal or other person kept in jail over night. •(UK, slang) A client of a prostitute who has paid for the entire night. formsall nighters · all-nighters