Enthymeme
Etymology
From Greek "enthymēma," "a thought" or "a piece of reasoning," from "enthymeisthai," "to keep in mind" or "to consider," built from "en," "in," and "thymos," "mind" or "spirit." Aristotle treated the enthymeme as the workhorse of rhetoric — a compressed syllogism that trusts the listener to supply the missing part. Its power and its danger are the same: the unstated premise slips by unexamined.
noun · /EN-thuh-meem/
An argument in which one premise is left unstated because it is assumed to be understood.
What it names
The argument with a hidden step — the way most real persuasion works, by leaning on a premise the audience already accepts and never says aloud.
Example
"She went to Harvard, so she’ll be great at this" is an enthymeme resting on an assumption nobody in the room stated.
Related idea
An enthymeme is a syllogism with a premise suppressed; making that hidden premise explicit is often the fastest way to see whether the argument actually holds.