taru-adjective, adverb taking the 'to' particle
hazy consciousness; half-conscious; dopey
Describes a state of clouded or dim consciousness, often due to illness, injury, exhaustion, or intoxication. Used as a たる adjective or adverbially with と.
熱で意識朦朧としている。
I'm in a hazy state of consciousness due to the fever.
事故の後、彼は意識朦朧としたまま病院に運ばれた。
After the accident, he was taken to the hospital while only half conscious.
Yojijukugo composed of 意識 (consciousness) and 朦朧 (dim, hazy). The exact historical derivation is uncertain, but the combination directly expresses a clouded state of awareness.