siphon off vs syphon

siphon off is not a noun while syphon is a noun.

Word	Noun	Adjective	Verb	Adverb
siphon off	No	No	Yes	No
syphon	Yes	No	Yes	No

As verbs, siphon off and syphon are synonyms defined as:

siphon off and syphon: convey, draw off, or empty by or as if by a siphon

Other synonyms of siphon off include siphon.

siphon off (noun)	syphon (noun)
	a tubular organ in an aquatic animal (especially in mollusks) through which water can be taken in or expelled
	a tube running from the liquid in a vessel to a lower level outside the vessel so that gravity forces the liquid through the tube

siphon off (verb)	syphon (verb)
convey, draw off, or empty by or as if by a siphon	convey, draw off, or empty by or as if by a siphon