Definitions

1. interjection

an expression used to greet someone or to get someone’s attention

“She said ‘hi’ to her friend as she walked by.”

2. noun

a greeting, especially one used to acknowledge someone’s presence

“After the meeting, she gave a hi to everyone in the room.”

3. verb

to greet someone

“He hi-ed his neighbor in the hallway.”

4. adverb

in a friendly or casual manner

“She hi’d her coworker in a friendly way.”