taru-adjective, adverb taking the 'to' particle
messy; cluttered; disorderly; chaotic
Describes a state of disorder, often used for physical spaces like rooms or piles, but also for abstract things like thoughts, lifestyles, or atmospheres. Commonly used with と as an adverb (雑然としている).
彼の部屋は雑然としていて、足の踏み場もない。
His room is so messy there's no place to step.
机の
Papers are piled up messily on the desk.
散らかる is a verb meaning 'to be in disorder' or 'to be messy', often used for rooms. 雑然 is more formal and emphasizes a chaotic, jumbled state, often used in written descriptions.
乱雑 also means 'disorderly' or 'messy', but is more commonly used as a noun or na-adjective. 雑然 is a taru-adjective, giving it a more literary or formal feel.
Compound of 雑 (miscellaneous, mixed) and 然 (state, condition), literally 'in a mixed state'. The exact historical derivation is uncertain, but the kanji combination conveys the meaning of disorder.