ILLEGALLY
illegally, illicitly, lawlessly
(adverb) in an illegal manner; “they dumped the waste illegally”
Source: WordNet® 3.1
Etymology
Adverb
illegally (comparative more illegally, superlative most illegally)
In a manner contrary to law.
Antonyms
• legally
Source: Wiktionary
Il*le"gal*ly, adv.
Definition: In a illegal manner; unlawfully.
ILLEGAL
Il*le"gal, a. Etym: [Pref. il- not + legal: cf. F. illégal.]
Definition: Not according to, or authorized by, law; specif., contrary to,
or in violation of, human law; unlawful; illicit; hence, immoral; as,
an illegal act; illegal trade; illegal love. Bp. Burnet.
Source: Webster’s Unabridged Dictionary 1913 Edition