Hi

Abbreviation of Hello, an informal greeting. Depending on the tone or situation it is used in, it could be interpreted as either a quicker greeting, or an indicator that something is wrong and/or the speaker would prefer not to talk with the person who initiated conversation. People use ‘hi’ in such drastically different ways because it in itself is known as a polite term, used for greeting. It’s considered more polite to convey meaning in a solemn ‘hi’ rather than ‘Go away.’ or ‘I’m not well enough to carry this conversation.’