A NIMBY is someone who's opposed to an organization, building, or project being located too close to where they live. NIMBY stands for "not in my backyard."
NIMBYs often approve of a new development, but they want it sited as far away from them as possible. When something like a homeless shelter, prison, wind turbine, drug treatment center, or airport is proposed, a NIMBY may speak up in support of the project but object strongly to its location on his or her own street. The word NIMBY, or nimby, is an acronym for "not in my back yard," which first appeared in American English around 1980.