scream vs halloo

scream and halloo both are nouns.

Word	Noun	Adjective	Verb	Adverb
scream	Yes	No	Yes	No
halloo	Yes	No	Yes	No

As verbs, halloo is a hyponym of scream; that is, halloo is a word with a more specific, narrower meaning than scream:

scream (noun)	halloo (noun)
sharp piercing cry	a shout to attract attention
a joke that seems extremely funny
a high-pitched noise resembling a human cry

scream (verb)	halloo (verb)
utter a sudden loud cry	shout `halloo', as when greeting someone or attracting attention
utter or declare in a very loud voice	urge on with shouts
make a loud, piercing sound