taru-adjective, adverb taking the 'to' particle, noun which may take the genitive case particle 'no'
Describes someone who speaks their mind boldly and directly, often in a formal or literary context. Typically used as a たる adjective or with と adverbially.
彼は諤々たる意見を述べた。
He expressed his frank opinion.
会議で諤々と議論する。
They argue candidly at the meeting.
Variant spelling without the repetition mark; less common but still encountered.
率直 is the common, everyday word for 'frank' or 'straightforward'. 諤々 is more literary and emphasizes outspokenness with a bold, sometimes argumentative nuance.
直言 means 'speaking plainly' or 'telling it like it is', often used as a noun or する verb. 諤々 is an adjective/adverb and carries a more classical, forceful tone.
The exact derivation is uncertain. The kanji 諤 means 'speaking honestly' or 'outspoken', and the reduplication intensifies the meaning. It is a literary Sino-Japanese word.