furtive – secretive, artful, calculating, cautious, circumspect, clandestine, cloaked, conspiratorial, covert, crafty*, creep, cunning, disguised, elusive, evasive, foxy, guileful.

oppress – subdue, trample, tyrannize.

doctrine – axiom, belief, tenet.

priceless – incomparable, inestimable, invaluable, irreplaceable,

If you don’t, check out online dictionary. Search Google for more option.

synonym (plural synonyms)

A word or phrase that has a meaning the same as, or very close to, that of another word or phrase.

Happy is synonym with joyful.

furtive – sly. secretive. stealthy. sneaky. surreptitious

oppress – keep down. coerce. dominate. tyrannize. repress

doctrine – principle. canon. dogma. policy. guidelines.

priceless- inestimable. invaluable. incalculate. expensive. costly.

sorry if i can’t provide more for sidle

furtive:idk

opress:idk

doctrine:idk

priceless:free