hollo vs let out

hollo is a noun but let out is not a noun.

Word	Noun	Adjective	Verb	Adverb
hollo	Yes	No	Yes	No
let out	No	No	Yes	No

As verbs, let out is a hypernym of hollo; that is, let out is a word with a broader meaning than hollo:

Other hypernyms of hollo include emit, let loose, utter.

hollo (noun)	let out (noun)
a very loud utterance (like the sound of an animal)

hollo (verb)	let out (verb)
utter a sudden loud cry	make (clothes) larger
cry hollo	make known to the public information that was previously known only to a few people or that was meant to be kept a secret
encourage somebody by crying hollo	express audibly; utter sounds (not necessarily words)
	bring out of a specific state