taru-adjective, adverb taking the 'to' particle
Rare literary term used in classical or formal writing to describe something clearly evident, bright, or manifest. Often appears in the adverbial form 昭昭として.
彼の功績は昭昭たる事実である。
His achievements are a clear and undeniable fact.
真実は昭昭として目の前にある。
The truth is plainly evident before our eyes.
Standard formal term for 'obvious, clear'. 昭昭 is more archaic and emphatic.
Reduplication of 昭 (しょう, 'bright, clear'), emphasizing clarity or obviousness. The exact historical derivation is uncertain; the spelling is conventionally associated with these meanings.