taru-adjective, adverb taking the 'to' particle
bright; shining; clear; evident
Obsolete literary term used in classical Chinese-influenced writing. Describes something vividly bright, shining, or clearly evident. Modern Japanese would use 明らか or 鮮明 instead.
古い漢文では、「炳乎として明らかなり」のように使われた。
In old kanbun texts, it was used like 'bright and clear as day'.