hallo

[huh-loh] /həˈloʊ/
interjection
1.
(used to call or answer someone, or to incite dogs in hunting.)
noun, plural hallos.
2.
the cry “hallo!”.
3.
a shout of exultation.
verb (used without object), halloed, halloing.
4.
to call with a loud voice; shout; cry, as after hunting dogs.
verb (used with object), halloed, halloing.
5.
to incite or chase (something) with shouts and cries of “hallo!”.
6.
to cry “hallo” to (someone).
7.
to shout (something).
Also, halloa, halloo, hallow, hillo, hilloa, hullo, hulloo.
Origin
1560-70; variant of hollo, itself variant of earlier holla < Middle French hola, equivalent to ho ahoy + la there
British Dictionary definitions for hallo

hallo

/həˈləʊ/
sentence substitute, noun
1.
a variant spelling of hello
sentence substitute, noun, verb
2.
a variant spelling of halloo

halloo

/həˈluː/
sentence substitute
1.
a shout to attract attention, esp to call hounds at a hunt
noun (pl) -loos, -los, -loas
2.
a shout of "halloo"
verb -loos, -looing, -looed, -los, -loing, -loed, -loas, -loaing, -loaed
3.
to shout (something) to (someone)
4.
(transitive) to urge on or incite (dogs) with shouts
Word Origin
C16: perhaps variant of hallow to encourage hounds by shouting

hello

/hɛˈləʊ; hə-; ˈhɛləʊ/
sentence substitute
1.
an expression of greeting used on meeting a person or at the start of a telephone call
2.
a call used to attract attention
3.
an expression of surprise
4.
an expression used to indicate that the speaker thinks his or her listener is naive or slow to realize something: Hello? Have you been on Mars for the past two weeks or something?
noun (pl) -los
5.
the act of saying or calling "hello"
Word Origin
C19: see hallo
Word Origin and History for hallo

shout to call attention, 1781, earlier hollo, holla (see hello). Halow as a shipman's cry to incite effort is from mid-15c.; Halloo as a verb, "to pursue with shouts, to shout in the chase," from late 14c. Cf. also harou, cry of distress, late 13c., from French.