taru-adjective, adverb taking the 'to' particle
Literary たる adjective describing a state where something is plainly apparent. Often used in the adverbial form 瞭然と.
His lie was obvious.
The evidence is clear.
obvious; clear as day; plain to see
Standard kanji form; 瞭 is a 常用漢字, making this the preferred spelling.
Variant using the simpler 了; less common but still encountered.
From Chinese 瞭然/了然. The exact historical derivation is uncertain; the spelling is conventionally associated with clarity and obviousness.