swill vs swill down

swill is a noun but swill down is not a noun.

Word	Noun	Adjective	Verb	Adverb
swill	Yes	No	Yes	No
swill down	No	No	Yes	No

As verbs, swill and swill down are synonyms defined as:

swill and swill down: drink large quantities of (liquid, especially alcoholic drink)

swill (noun)	swill down (noun)
wet feed (especially for pigs) consisting of mostly kitchen waste mixed with water or skimmed or sour milk

swill (verb)	swill down (verb)
drink large quantities of (liquid, especially alcoholic drink)	drink large quantities of (liquid, especially alcoholic drink)
feed pigs