"Lost thought" is a phrase that typically refers to an idea or memory that slips from one's mind. There are several synonyms that can be used to describe this type of mental slip-up, including "brain freeze," "mental lapse," "forgetfulness," "cognitive blunder," and "lack of recall." Each of these phrases puts a slightly different spin on the concept of temporarily losing a thought, but all convey the idea of a fleeting or elusive mental state. Whether you're struggling to remember a name, an errand you need to run, or an important piece of information, it's comforting to know that you're not alone in experiencing these occasional hiccups of the mind.