Hi

Part of speech: interjection

Definitions

1. An informal word spoken to acknowledge someone when you first meet them or see them arrive
2. A casual salutation used to greet a person as a friendly way of saying hello
3. Used as a friendly, casual exclamation to greet someone when encountering them

Etymology: "Hi" is a greeting that began as a call to attract attention. Its first recorded use in print is in 1862, in the speech of a Kansas Indian, and at that stage it simply meant something like "hey!" It is probably a variant of "hey", the older exclamation for calling someone's notice, which goes back to around 1475. The greeting sense developed afterward from that attention-getting function, as people began using it to acknowledge someone who had come into view.

Synonyms: hello, hey, hiya, greetings

Antonyms: bye, goodbye