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

Encyclopedia: Perchance

• unstableness
• unstaged
• unstained
• unstaple
• unstarred
• prestigious
• prestigiousness
• prestissimo
• presto
• Preston
• prestressed
• presumable
• presumably
• presume
• presumption
• presumptive
• presumptively
• presumptuous
• presumptuously
• presumptuousness
• presuppose
• presupposition
• presymptomatic
• preteen
• preteenager