A lot vs. Alot: 9 Grammatical Pitfalls
1882, from epi- + dura (mater) (see dura mater). The noun meaning "injection into the epidural region" (usually during childbirth) is attested by 1970.
epidural ep·i·du·ral (ěp'ĭ-dur'əl, -dyur'-)adj. Located on or over the dura mater. n. An injection into the epidural space of the spine.