noun
entity declaration
Technical term used in computing contexts such as XML, SGML, or markup languages to define an entity.
XMLでは、実体宣言を使って特殊文字を定義できる。
In XML, you can define special characters using entity declarations.
Compound of 実体 (entity) and 宣言 (declaration), likely a calque from English 'entity declaration' used in computing.