1. By chance
   - possibly, perhaps, maybe, mayhap [archaic], peradventure [archaic] 
2. [archaic] Through chance, "To sleep, perchance to dream.."
   - by chance [archaic]

Encyclopedia: Perchance

• unpunished
• unpurified
• unputdownable
• Unq
• unqualified
• unqualifiedly
• unquenchable
• unquestionability
• unquestionable
• unquestionableness
• unquestionably
• unquestioned
• unquestioning
• unquestioningly
• unquiet
• unquietly
• unquotable
• unquote
• unraised
• unranked
• unratable
• unrated
• unratified
• unravel
• unraveler