A somewhat literary or formal adverb meaning that something happens without prior expectation or by coincidence. Often used in written Japanese or polite speech.
Unexpectedly, I ended up meeting him again.
By chance, I came to know that secret.
Kanji spelling using 端. Rarely used; the kana form is strongly preferred.
Kanji spelling using 端無. Rarely used; the kana form is strongly preferred.
From the classical adjective はしなし “unexpected, unforeseen,” in its adverbial form はしなく, followed by the particle も.