虹吸 (hóng xī) literally means 'rainbow suction'—'虹' refers to a rainbow, evoking the curved shape of a siphon tube, and '吸' means 'to suck' or 'to draw in.' Together, they form a technical noun describing the physical process where liquid flows upward and over a barrier due to atmospheric pressure and gravity, without a pump. Though the name is poetic, the term is used in engineering, agriculture, aquarium maintenance, and household contexts.

In Chinese, 虹吸 appears most often in scientific or practical descriptions—not in casual speech—and frequently co-occurs with words like '管' (tube), '现象' (phenomenon), or '效应' (effect). It's commonly taught in middle-school physics and appears in manuals for water features, hydroponic systems, and pond filtration. While visually reminiscent of a rainbow’s arc, the term carries no metaphorical or literary connotation—it is strictly functional and descriptive.