licensed

Compared meaning: approved or authorized by authority (adjective).

比较义项：得到官方或权威机构认可、许可（形容词）。

• official

  Describes something as authorized or issued by a government, institution or person in charge, e.g. official documents, an official language, an official announcement; not about tone or manner.

  表示某事物由政府、机构或负责人批准或发布，如官方文件、官方语言、官方声明；不涉及语气或礼节。

  French is the official language taught in every public school here.

  法语是这里每所公立学校教授的官方语言。

• formal

  Describes manner, dress or language that follows accepted customs and shows seriousness or respect, as opposed to casual; not necessarily backed by government authority.

  形容遵循礼节规范、显得庄重得体的举止、着装或语言，与随便非正式相对；不一定有政府权威作后盾。

  He always uses formal language when writing emails to his professor.

  他给教授写邮件时总是使用正式的语言。

• licensed 本词

  Describes a person or business that has passed official requirements and holds a certificate or permit to practise a trade or profession, e.g. a licensed electrician.

  形容某人或某机构通过官方要求的考核，持有从事某行业或职业的证书或许可证，如持证电工。

  He works as a licensed electrician for a local construction company.

  他在一家本地建筑公司担任持证电工。

Official, formal, and licensed can all relate to authority, but differ. Official means authorized by a government or institution, like an official document. Formal describes manner, dress, or language following accepted customs. Licensed means holding an official certificate to practice a trade.

这三个词都可译作“正式的”或与权威、许可有关，容易混淆：official 强调具有官方地位或经权威机构批准，formal 强调遵循礼仪规范、举止庄重，licensed 强调持有官方颁发的执照或许可证。这里不比较 official 作名词“官员”的用法。