"the 'genius' of a people, characteristic spirit of a time and place," 1851 (Palgrave) from Greek ethos "habitual character and disposition; moral character; habit, custom; an accustomed place," in plural, "manners," from suffixed form of PIE root *s(w)e- third person pronoun and reflexive (see idiom). An important concept in Aristotle (as in "Rhetoric" II xii-xiv).