sough vs purl

sough is not a noun while purl is a noun.

Word	Noun	Adjective	Verb	Adverb
sough	No	No	Yes	No
purl	Yes	No	Yes	No

As verbs, sough and purl are synonyms defined as:

sough (noun)	purl (noun)
	a basic knitting stitch made by putting the needle through the front of the stitch from the righthand side
	gold or silver wire thread

sough (verb)	purl (verb)
make a murmuring sound	make a murmuring sound
	embroider with gold or silver thread
	edge or border with gold or silver embroidery
	knit with a purl stitch
	flow in a circular current, of liquids