Barrer

Part of speech: noun

Definitions

1. A piece of material or object used to obstruct or prevent passage through a road, doorway, or similar opening
2. An individual who performs the act of blocking or hindering someone's movement or access
3. A term denoting a barrier or object that blocks an entrance or passageway

Etymology: The most surprising strand is that one sense of this word is named after a person. It is a unit of gas permeability, named after Richard Barrer, a New Zealand-born chemist who studied how gases pass through materials. The rest of the word is plainly built. It combines "bar", inherited through Old French "barre" from Vulgar Latin "barra", with the agent suffix "-er". That suffix descends from Latin "-arius", which passed through Old French "-ier" and Middle English "-er". The sense of "something that bars" or "blocks passage" follows directly from that combination, which is why it fits the meaning you gave.