To greet with "hello".
A greeting used when answering the telephone.
A call for response if it is not clear if anyone is present or listening, or if a telephone conversation may have been disconnected.
An expression of puzzlement or discovery.
Used sarcastically to imply that the person addressed or referred to has done something the speaker or writer considers to be foolish.
A greeting (salutation) said when meeting someone or acknowledging someone’s arrival or presence.
"Hello!" or an equivalent greeting.
A phrase used at parting, and not necessarily implying that the person being addressed will be seen later by the speaker.