What characteristic does something described as "ephemeral" possess?

Something described as "ephemeral" possesses the characteristic of being fleeting or short-lived. The term derives from the Greek word "ephemeros," which means "lasting only a day." This is often used to refer to things that have a brief existence, such as certain flowers that bloom for only one day, or experiences that are momentary and quickly pass. The essence of ephemerality highlights the beauty and transience of these subjects, underscoring that they are not meant to last.

In the context of the other choices, they do not align with the meaning of "ephemeral." Something that lasts a long time, is permanent, or is substantial and heavy contradicts the very nature of what it means to be ephemeral. Thus, understanding the word within this framework helps clarify its specific meaning and application.