A flat road stretched on endlessly.
taru-adjective, adverb taking the 'to' particle
uneventful; peaceful; monotonous
Describes a situation, life, or mood that is calm, without trouble or excitement, sometimes with a nuance of monotony. Often used with とした.
He leads a peaceful, uneventful life.
Full-character repetition form; less common than 坦々 but still seen.
Reduplication of 坦 (tan, 'flat, level'), forming a taru-adjective/adverb. The exact historical derivation is uncertain, but the form follows a classical pattern for descriptive words.