"Hello!" or an equivalent greeting.

To greet with "hello".

A greeting (salutation) said when meeting someone or acknowledging someone’s arrival or presence.

Example: Hello, everyone.

A greeting used when answering the telephone.

Example: Hello? How may I help you?

A call for response if it is not clear if anyone is present or listening, or if a telephone conversation may have been disconnected.

Example: Hello? Is anyone there?

Used sarcastically to imply that the person addressed or referred to has done something the speaker or writer considers to be foolish.

Example: You just tried to start your car with your cell phone. Hello?

An expression of puzzlement or discovery.

Example: Hello! What’s going on here?