Antonym: formal. Similar words: information, formal, normally, inform, format, in force, go in for, reinforce. Meaning: [ɪn'fɔrml / -'fɔːml] 
adj. 1. not formal 2. not officially recognized or controlled 3. used of spoken and written language 4. having or fostering a warm or friendly and informal atmosphere.
adj. 1. not formal 2. not officially recognized or controlled 3. used of spoken and written language 4. having or fostering a warm or friendly and informal atmosphere. 
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1) Our meetings are relatively informal.
2) The atmosphere at work is fairly informal.
3) Each course comprises 10-12 informal weekly meetings.
4) The two groups agreed to hold an informal meeting.
5) I got an informal reception.
6) Discussions are held on an informal basis within the department.
7) I meant it to be an informal discussion, but it didn't turn out as I intended .
8) Informal interaction among employees is seen as part of the ongoing training process.
9) The aim of the trip was to make informal contact with potential customers.
10) The two groups met for informal talks.
11) She's giving a small informal party this evening.
12) Don't fuss up for the party,(http://sentencedict.com/informal.html)it's very informal.
13) Sometimes formal English and informal English are undistinguished.
14) The leaders met over informal lunches.
15) Many informal expressions are gaining currency in serious newspapers.
16) Plant daffodils in informal drifts.
17) The restaurant is informal, stylish and extremely good value.
18) Holmes used an informal, chatty tone in his essays.
19) The house has an informal atmosphere.
20) The coaching is informal and tailored to individual needs.
21) The couple relied on informal care from relatives.
22) This coat was dirt cheap informal .
23) 'Hi' is an informal way of greeting people.
24) Her speech is informal and filled with colloquialism.
25) The course includes formal lectures and more informal seminars.
26) Dress at the party was informal, with no neckties or fancy dresses.
27) We don't have a proper agreement, but we have an informal understanding, if you like.
28) He's the ideal sort of teacher - direct, friendly and informal.
29) I bought a dozen eggs and every one of them was bad. A plural verb is more informal.
30) After the lecture there will be an opportunity for informal discussion.
More similar words: information, formal, normally, inform, format, in force, go in for, reinforce, formation, transformation, mall, small, male, dismal, female, unfold, German, minimal, enforce, on foot, fisherman, chairman, design for, form, norm, supermarket, infant, in full, in fact, malfunction.