Merriam-Webster Online Dictionary
illegal (adjective)not according to or authorized by law - unlawful illicit , also not sanctioned by official rules (as of a game)
an illegal immigrant
Merriam-Webster Online Thesaurus
illegal (adjective)1.
contrary to or forbidden by law
SYNONIMS:
criminal, felonious, illegitimate, illicit, lawless, unlawful, wrongfulRELATED WORDS:
bad, evil, immoral, shameful, sinful, unethical, wicked, wrong; blamable, blameworthy, censurable, reprehensible; banned, barred, contraband, criminalized, disallowed, discouraged, forbidden, interdicted, outlawed, prohibited, proscribed; adulterine, bootleg, unauthorized, unlicensed, unsanctioned; under-the-counter, under-the-table; corrupt, unprincipled, unscrupulous, villainousNEAR ANTONYMS:
ethical, good, just, principled, right, righteous, virtuous; allowed, permitted; authorized, licensed; approved, endorsed ( indorsed), sanctioned; abetted, encouraged, promoted, suggested, supported; correct, decent, decorous, proper, seemly2.
not being in accordance with the rules or standards of what is fair in sport
SYNONIMS:
dirty, illegal, nasty, unfair, unsportsmanlikeRELATED WORDS:
dishonorable, shabby, shameful; ignoble, low, mean, ungentlemanly; immoral, rotten, unchivalrous, unethical, unjust, unprincipled, unrighteous, unscrupulousNEAR ANTONYMS:
just, law-abiding; ethical, moral, principled, righteous, scrupulous; honorable, irreproachable, unimpeachable