" There is a term (a noun) "understudy" which refers to a person, typically a performer, who learns all of the lines of another character in case he/she needs to take over the role. " It is not grammatically incorrect, however. This construction is used often, "under review," "under advisement," etc.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
Anonymousseldom used = rarely used??Yes.
AnonymousAre there several ways to state the same concept?Always.