n (photography) A chemical (sodium thiosulfate) used in photographic development that fixes the image in place, preventing further chemical reactions.
n (Criminal justice, law, and underworld) A person who arranges immunity for defendants by tampering with the justice system via bribery or extortion, especially as a business endeavor for profit.
n (journalism) A person who assists foreign journalists in volatile countries, they often provide interpretation, personal connections, and transportation as a service.