godan verb (-mu), intransitive verb
to become luminous at dawn; to lighten (sky)
Rare literary verb, especially for the sky growing light at daybreak. Modern Japanese normally uses 明るむ (あかるむ) or 明ける (あける).
東の空が明らむころ、鳥たちが鳴き始めた。
As the eastern sky began to lighten, the birds started singing.
Literary kanji form; the word is rare and mostly encountered in classical or poetic contexts.
Kana spelling is practical for learners and avoids confusion with more common 明るむ (あかるむ).
Derived from classical Japanese 明らむ (あからむ), related to 明るい (あかるい, 'bright'). The exact historical derivation is uncertain.