Cases of word usage

1) a word that is popular in informal speech (usually for a short period) (catchword)

2) a friendly, informal talk (chat)

3) informal conversation (chitchat)

4) an informal business communication (memorandum)

5) an informal and friendly remark (pleasantry)

6) a member of 'the Quakers' or the 'Society of Friends', a Christian group that holds informal meetings and is opposed to violence (quaker)

7) an informal meeting of friends to sing songs together (singsong)

8) words, phrases, meanings etc sometimes used in very informal conversation but not suitable for writing or for more formal occasions (slang)

9) living in groups, not separately; an informal gathering for eating, dancing etc, especially organized by a club (social)

10) a conversation; discussion; gossip; an informal speech (talk)