sidelong vs obliquely

sidelong is an adjective but obliquely is not an adjective.

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

As adverbs, sidelong and obliquely are synonyms defined as:

Other synonyms of sidelong include sideways.

sidelong (adjective)	obliquely (adjective)
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

sidelong (adverb)	obliquely (adverb)
to, toward or at one side	at an oblique angle
with the side toward someone or something	to, toward or at one side
on the side