curtain hung at the doorway or entrance to a room," 1843, from French portière, which is formed in French from porte "door," or from Medieval Latin portaria, fem. singular of Latin portarius "belonging to a door or gate," from porta "city gate, gate; door, entrance," from PIE root *per- (2) "to lead, pass over."
A curtain hung at a doorway, or entrance to a room, either with the door or to replace it, to intercept the view or currents of air, etc., when the door is opened, or for mere decoration. [Century Dictionary]
1690s (in reference to both the cartilage and the gland), from Greek thyreoeides "shield-shaped" (in khondrosthyreoeides "shield-shaped cartilage," used by Galen to describe the "Adam's apple" in the throat), from thyreos "oblong, door-shaped shield" (from thyra "door," from PIE root *dhwer- "door, doorway") + -eides "form, shape" (see -oid). The noun, short for thyroid gland, is recorded from 1849.
["doorkeeper, janitor"] mid-13c. (late 12c. as a surname), "one who has charge of a door or gate; one who guards the gate of a bridge," from Anglo-French portour, Old French portier "gatekeeper" (12c.), from Late Latin portarius "gatekeeper," from Latin porta "city gate, gate; door, entrance," from PIE root *per- (2) "to lead, pass over."