hello
[hə'lo]
interj. 喂, 嘿



hello
[ noun ]
an expression of greeting
<noun.communication>
every morning they exchanged polite hellos



Hello \Hel*lo"\, interj. & n.
An exclamation used as a greeting, to call attention, as an
exclamation of surprise, or to encourage one. This variant of
{Halloo} and {Holloo} has become the dominant form. In the
United States, it is the most common greeting used in
answering a telephone.
[1913 Webster +PJC]