The Rice University Neologisms Database

Loss of concentration or loss of a particular thought; a senior moment. A brain fart may be considered an event in which a person cannot say or bring a simple concept, idea or fact to conscious thought. This term is used to describe the event in which a person is for a short period of time unable to remember a particular thought or the thought might be at “the tip of their tongue." Often times one may experience a brain fart when speaking with a group of people. Instead of calling this embarrassing short-term loss of memory a “brain fart” the individual may just be more polite and say, “Oh! I forgot what I was going to say.”