Definition of chat noun from the Oxford Advanced Learner's Dictionary
chat
noun
tʃæt tʃæt
1[countable] (especially British English) a friendly informal conversationI just called in for a chat.I had a long chat with her.2[uncountable]talking, especially informal conversationThat's enough chat from me—on with the music!3[uncountable, countable]communication between people on the Internetchat softwareInternet chat servicesFans are invited to an online chat.a guide to Internet chat safety for childrenUsage note: discussionconversationdialoguetalkdebateconsultationchatgossipThese are all words for an occasion when people talk about something.discussion a detailed conversation about something that is considered to be important: Discussions are still taking place between the two leaders.conversation a talk, usually a private or informal one, involving two people or a small group; the activity of talking in this way: a telephone conversationdialogue conversations in a book, play or film: The novel has long descriptions and not much dialogue. A dialogue is also a formal discussion between two groups, especially when they are trying to solve a problem or end a dispute: The President told waiting reporters there had been a constructive dialogue.talk a conversation or discussion, often one about a problem or something important for the people involved: I had a long talk with my boss about my career prospects.debate a formal discussion of an issue at a public meeting or in a parliament. In a debate two or more speakers express opposing views and then there is often a vote on the issue: a debate on prison reformconsultation a formal discussion between groups of people before a decision is made about something: There have been extensive consultations between the two countries.chat a friendly informal conversation; informal talking. The countable use of chat is especially British English: I just called in for a chat about the kids.gossip a conversation about other people and their private lives: We had a good gossip about the boss.a discussion/conversation/dialogue/talk/debate/consultation/chat/gossip about somethinga discussion/conversation/dialogue/debate/consultation on somethingin (close) discussion/conversation/dialogue/debate/consultation with somebodyto have a discussion/conversation/dialogue/talk/debate/consultation/chat/gossip with somebodyto hold a discussion/conversation/debate/consultation
tʃæt 
tʃæt 
1 [countable] (especially British English) a friendly informal conversationI just called in for a chat.I had a long chat with her.2 [uncountable] talking, especially informal conversationThat's enough chat from me—on with the music!3 [uncountable, countable] communication between people on the Internetchat softwareInternet chat servicesFans are invited to an online chat.a guide to Internet chat safety for children
Usage note: discussionconversation dialogue talk debate consultation chat gossipThese are all words for an occasion when people talk about something.discussion a detailed conversation about something that is considered to be important: Discussions are still taking place between the two leaders.conversation a talk, usually a private or informal one, involving two people or a small group; the activity of talking in this way: a telephone conversationdialogue conversations in a book, play or film: The novel has long descriptions and not much dialogue. A dialogue is also a formal discussion between two groups, especially when they are trying to solve a problem or end a dispute: The President told waiting reporters there had been a constructive dialogue.talk a conversation or discussion, often one about a problem or something important for the people involved: I had a long talk with my boss about my career prospects.debate a formal discussion of an issue at a public meeting or in a parliament. In a debate two or more speakers express opposing views and then there is often a vote on the issue: a debate on prison reformconsultation a formal discussion between groups of people before a decision is made about something: There have been extensive consultations between the two countries.chat a friendly informal conversation; informal talking. The countable use of chat is especially British English: I just called in for a chat about the kids.gossip a conversation about other people and their private lives: We had a good gossip about the boss.a discussion/conversation/dialogue/talk/debate/consultation/chat/gossip about somethinga discussion/conversation/dialogue/debate/consultation on somethingin (close) discussion/conversation/dialogue/debate/consultation with somebodyto have a discussion/conversation/dialogue/talk/debate/consultation/chat/gossip with somebodyto hold a discussion/conversation/debate/consultation