syphon vs siphon off

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

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

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

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

Other synonyms of syphon include siphon.

syphon (noun)	siphon off (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

syphon (verb)	siphon off (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