Ethos
Etymology
From Greek ēthos, “custom, character, disposition.” In Aristotle’s rhetoric it named the speaker’s credibility of character, one of the three modes of persuasion alongside logos and pathos. From “character” it broadened to the defining spirit of a whole community.
noun · /EE-thoss/
The characteristic spirit, values, and attitudes of a community, culture, or era.
What it names
The felt character of a group — the shared disposition that shows up in how people there actually behave, distinct from its stated rules.
Example
The startup’s ethos of “ship fast and apologize later” explained both its wins and its messes.
Related idea
An ethos is a group’s inner character and values; a milieu is the surrounding social environment itself.