tether vs leash

tether and leash both are nouns.

Word	Noun	Adjective	Verb	Adverb
tether	Yes	No	Yes	No
leash	Yes	No	Yes	No

As nouns, tether and leash are synonyms defined as:

tether and leash: restraint consisting of a rope (or light chain) used to restrain an animal

Other synonyms of tether include lead.

tether (noun)	leash (noun)
restraint consisting of a rope (or light chain) used to restrain an animal	a figurative restraint
	restraint consisting of a rope (or light chain) used to restrain an animal
	the cardinal number that is the sum of one and one and one

tether (verb)	leash (verb)
tie with a tether	fasten with a rope