All by chance synonyms

adv by chance

• accidentally — happening by chance or accident; not planned; unexpected: an accidental meeting.
• unexpectedly — not expected; unforeseen; surprising: an unexpected pleasure; an unexpected development.
• unintentionally — not intentional or deliberate: an unintentional omission from the list.
• unwittingly — inadvertent; unintentional; accidental: His insult, though unwitting, pained her.
• as luck would have it — fortunately
• by mistake — accidentally, not on purpose
• fortuitous — happening or produced by chance; accidental: a fortuitous encounter.