headwall

== English == === Etymology === From head +‎ wall. === Noun === headwall (plural headwalls) (geography) The highest cliff of a glacial cirque. (geology) The steep cliff at the back of a cirque. (civil engineering) A retaining wall at the outlet of a drain, culvert or tunnel. === References === “headwall”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.