informal

irregular, casual, informal

形容词 informal:

1. not formal
2. not officially recognized or controlled
   同义词：loose
3. used of spoken and written language
4. having or fostering a warm or friendly and informal atmosphere
   同义词：cozy, intimate

1. I meant it to be an informal discussion, but it didn't turn out as I intended (it should).
   我本想随便商量一下，结果事与愿违。
2. An informal dance or party arranged to give members of a group an opportunity to get acquainted.
   交谊会一个非正式的舞蹈或聚会，用以给一群成员安排认识的机会
3. An informal gathering or session for the exchange of news, opinions, and gossip.
   非正式的聚会，杂谈会为交换消息、意见或内幕新闻而进行的非正式聚会或会议
4. These words are informal.
   这些词是非正式用语。
5. We had an informal meeting.
   我们做了非正式的会晤。

in.for.mal

adj.（形容词）
Not formal or ceremonious; casual:
非正式的：不正式的，不正规的；随便的：
例句：
an informal gathering of friends; a relaxed, informal manner.
朋友们的非正式聚会；一种放松的、随便的方式

Not being in accord with prescribed regulations or forms; unofficial:
不拘礼节的：不遵从即定的规定和形式的；非官方的：
例句：
an informal agreement.
一项非正式决议

Suited for everyday wear or use:
日常的：适合于日常穿戴和用途的：
例句：
informal clothes.
日常的服装

Being more appropriate for use in the spoken language than in the written language.
口语的：更适合于日常口语，而不适于书面语言的

【引伸】
infor.mally
adv.（副词）