sideways vs sidelong

sideways and sidelong both are adjectives.

Word	Noun	Adjective	Verb	Adverb
sideways	No	Yes	No	Yes
sidelong	No	Yes	No	Yes

As adverbs, sideways and sidelong are synonyms defined as:

Other synonyms of sideways include obliquely.

sideways (adjective)	sidelong (adjective)
(of movement) at an angle	inclining or directed to one side
	(used especially of glances) directed to one side with or as if with doubt or suspicion or envy
	situated at or extending to the side

sideways (adverb)	sidelong (adverb)
to, toward or at one side	to, toward or at one side
from the side; obliquely	with the side toward someone or something
with one side forward or to the front	on the side
in a lateral direction