taru-adjective, adverb taking the 'to' particle
clouds or mist gathering thickly
Literary, descriptive word for the state of clouds or mist accumulating heavily. Used in classical or poetic contexts; cross-referenced with 靄然.
See also: 靄然
Clouds had gathered thickly over the mountaintop.
Reduplication of 靄 (あい, mist/haze), forming a literary descriptive word. The exact historical derivation is uncertain; the spelling is conventionally associated with misty or cloudy accumulation.