HTML 标签: dfn
A definition — the defining instance of a term.（一个定义 — 术语的定义实例。）
The paragraph, description list group, or section that the first instance of a specific dfn element appears in should also contain the definition of that term.（特定 dfn 元素首次出现的段落、描述列表组或部分也应包含该术语的定义。）
可选属性
示例
<p><dfn><abbr title="HyperText Markup Language">HTML</abbr></dfn> is a computer language used to structure web-based content.</p>
<p>HTML <dfn>tags</dfn> mark the beginning and end of HTML elements.</p>