mid-13c., contenaunce, “behavior, bearing, conduct, manners;” early 14c., “outward appearance, looks,” from Old French contenance “demeanor, bearing, conduct,” from Latin continentia “restraint, abstemiousness, moderation,” literally “way one contains oneself,” from continentem, present participle of continere “to hold together, enclose,” from assimilated form of com “with, together” (see con-) + tenere “to hold,” from PIE root *ten- “to stretch.”
The meaning evolved in late Middle English from “appearance” to “facial expression betraying or expressing a state of mind,” to “the face” itself. Hence also, figuratively, “aspect imparted to anything.”
