A solemn promise is also referred to as what?

A solemn promise is best referred to as an oath because it implies a serious, formal commitment to uphold a certain duty or to tell the truth. An oath is often taken in a ceremonial context and carries a significant weight of moral responsibility. It binds the individual not just to a promise on a personal level but also in a broader ethical context, often invoking a higher power or principle as witness to that promise. This distinguishes it from other forms of promises which may lack the same level of gravity or formal acknowledgment.

The other options represent forms of commitment or promises but do not necessarily possess the same solemnity or formal invocation that characterizes an oath. A commitment can be less formal, while a pledge and a covenant may also involve promises but may not denote the same level of binding seriousness as an oath. Thus, the strength and ceremonial nature of an oath make it the most suitable reference for a solemn promise.