The word "突变" (tūbiàn) is formed through the compounding of two distinct characters: "突," meaning "sudden" or "abrupt," and "变," meaning "change" or "transformation." Together, they create a compound noun that literally translates to "sudden change," specifically denoting a rapid and significant alteration, most commonly used in scientific contexts such as biology (for genetic mutation) or to describe any abrupt, qualitative shift in state or condition.