Hĕr'is-son, n.

(Synop., §130), n. [Fr. hérisson, O. Fr. ericon, Pr. erisson, Sp. erizo, Pg. ericio, ouriço, It. riccio, from Lat. ericius, equivalent to erinaceus, a hedgehog.] (Fort.) A beam or bar armed with iron spikes pointed outward, and turning on a pivot or rolling on wheels, used to block up a passage.