Final answer:
A competitive advantage that is short-lived is referred to as a transient competitive advantage, characterized by its short-term, changeable nature.
Step-by-step explanation:
A competitive advantage that lasts a very short period of time is known as a transient competitive advantage. This type of competitive advantage can be described as short term and easily changed, follows a pattern of short-term characteristics, and is considered unstable and short term. In contrast, a sustained competitive advantage refers to one that is long term, stable, and not easily changed.