What term describes something that is likely to vanish like vapor?

The term that describes something likely to vanish like vapor is "evanescent." This word conveys the idea of something that fades away quickly or is transient in nature, much like steam or mist that dissipates into the air. The connotation of evanescence refers to a brief and fleeting presence, highlighting the impermanence of certain experiences or phenomena.

In contrast, while terms like "elusive" and "ephemeral" may share related meanings, they emphasize different aspects. "Elusive" refers more to something that is difficult to catch or define. "Ephemeral" also deals with transience but is often used to describe things that last for a very short time. In this context, "evanescent" is the most precise descriptor of vanishing like vapor, focusing specifically on the aspect of fading away quickly or becoming invisible.