Memory RNA, also referred to as long-lived RNA or persistent RNA, is a type of RNA that is involved in long-term memory formation. There are several synonyms for memory RNA, including stable RNA, non-coding RNA, messenger RNA, and ribosomal RNA. Ribosomal RNA plays an important role in protein synthesis, while messenger RNA carries genetic information from DNA to the ribosome for protein synthesis. Stable RNA is a general term for any RNA molecule that is long-lived and not readily degraded. Non-coding RNA refers to any RNA molecule that is not translated into protein, including memory RNA. These synonyms are often used interchangeably to describe this important type of RNA involved in memory retention and are essential for the understanding of their function in the brain.