Mean time between failure (MTBF) is a term commonly used in reliability engineering to measure the mean time elapsed between two consecutive failures of a system. However, there are several synonyms for MTBF that are also used in this field, such as mean time to failure (MTTF), mean failure time (MFT), and average time to failure (ATTF). These terms are all related to the expected time between failures of a system and are often used interchangeably. However, it is important to note that each term may have slight differences in their calculation methods and interpretations, and they should be used appropriately depending on the context of the analysis.