Noun
erw (plural erws or erwau)
(historical) A medieval Welsh unit of surface area equal to 11664 sq ft, or about ¼ acre.
(military) Initialism of enhanced-radiation weapon.
(military) Acronym of explosive remnant of war.
Source: en.wiktionary.orgThe UN Mine Action Centre identified the main risks as coming from "ERW left behind by Israeli aerial and artillery weapon systems, or from militant caches targeted by the Israeli forces." Source: Internet