To inhale or suck in air or a substance; to draw something in by suction (e.g., inhale smoke, vacuum up debris, sponge up water).
寒い日だったので思わず深く吸い込んだ。
It was a cold day, so I involuntarily took a deep breath.
掃除機が小さな紙くずをすべて吸い込んだ。
The vacuum cleaner sucked up all the small pieces of paper.
スポンジが水をよく吸い込むので便利だ。
The sponge soaks up water well, so it's convenient.
To be swallowed up or engulfed (by a crowd, whirlpool, darkness, etc.); often used in passive constructions to indicate being absorbed or consumed.
彼は人波に吸い込まれて見失ってしまった。
He was swallowed up by the crowd and lost from sight.
夜の闇に街の灯が吸い込まれるように消えていった。
The city lights went out as if being swallowed by the darkness of night.