1. In a manner disapproved or not allowed by custom
   - illegitimately 
2. In an illegal manner
   - illegally, lawlessly

See also: illicit

Antonym: licitly

• whistle-stop tour
• whistleblower
• whistleblowing
• whistler
• whistlestop
• whistling
• whistling buoy
• whistling marmot
• whistling swan
• whit
• whit leather
• Whit-Tuesday
• white
• white admiral
• white alder
• white Anglo-Saxon Protestant
• white ant
• white arsenic
• white ash
• white aspen
• white avens
• white backlash
• white baneberry
• white basswood
• white bead