felonious (adj.)

• actionable
• anarchic
• anarchistic
• anomic
• black-market
• bootleg
• chargeable
• conscienceless
• contraband
• corrupt
• corrupted
• criminal
• crooked
• dark
• devious
• dishonest
• dishonorable
• doubtful
• dubious
• evasive
• fishy
• flawed
• fraudulent
• ill-gotten
• illegal
• illegitimate
• illicit
• immoral
• impermissible
• indirect
• iniquitous
• insidious
• irregular
• lawless
• nonlegal
• outlaw
• outlawed
• punishable
• questionable
• rotten
• shady
• shameless
• shifty
• sinful
• sinister
• slippery
• suspicious
• tricky
• unauthorized
• unconscientious
• unconscionable
• unconstitutional
• under-the-counter
• under-the-table
• underhand
• underhanded
• unethical
• unlawful
• unofficial
• unprincipled
• unsavory
• unscrupulous
• unwarrantable
• unwarranted
• wicked
• wrong
• wrongful