pant vs let loose

pant is a noun but let loose is not a noun.

Word	Noun	Adjective	Verb	Adverb
pant	Yes	No	Yes	No
let loose	No	No	Yes	No

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

Other hypernyms of pant include emit, let out, utter.

pant (noun)	let loose (noun)
a short labored intake of breath with the mouth open
(usually in the plural) a garment extending from the waist to the knee or ankle, covering each leg separately
the noise made by a short puff of steam (as from an engine)

pant (verb)	let loose (verb)
breathe noisily, as when one is exhausted	express audibly; utter sounds (not necessarily words)
utter while panting, as if out of breath	turn loose or free from restraint