過飽和(かほうわ)

かほうわ
noun
supersaturation
writtenacademictechnicalscience
1. the state in which a solution, vapor, or other system contains more of a dissolved or suspended substance than it would normally be able to hold at equilibrium
A scientific term for a metastable condition in which a solution, gas, or similar system holds more solute than its normal saturation limit. A supersaturated sugar solution, for example, will begin to crystallize as soon as a seed crystal or vibration triggers nucleation. The concept is central to chemistry, meteorology (supersaturated water vapor in clouds), and crystal growth. In everyday writing, the word is sometimes used metaphorically for a market or environment that is already overflowing with a particular thing.
過飽和(かほうわ)状態(じょうたい)になる。
To become supersaturated.
砂糖水(さとうみず)を過飽和(かほうわ)にしてから冷(ひ)やす。
Bring the sugar water to a supersaturated state, then cool it.
過飽和(かほうわ)水蒸気(すいじょうき)は、わずかな刺激(しげき)で水滴(すいてき)に変(か)わる。
Supersaturated water vapor will turn into water droplets at the slightest disturbance.
溶液(ようえき)を過飽和(かほうわ)にして、ゆっくりと冷却(れいきゃく)することで、美(うつく)しい結晶(けっしょう)を作(つく)ることができる。
By supersaturating the solution and cooling it slowly, you can produce beautiful crystals.

Composed of 過(か)- (excessive, over-) + 飽和(ほうわ) (saturation). Literally "over-saturation." A technical term used in chemistry, physics, and meteorology.

Common collocations

Scientific background

A saturated (飽和(ほうわ)) solution contains as much dissolved solute as the solvent can normally hold at a given temperature. If the temperature is lowered slowly and no disturbance occurs, the solution may hold more solute than the new saturation point allows — this is the supersaturated state. It is metastable: any small trigger (a seed crystal, dust particle, scratch on the container, or vibration) sets off rapid crystallization.

In meteorology, supersaturated water vapor is water vapor in the atmosphere that exceeds the equilibrium vapor pressure; it gives rise to cloud droplets, fog, and contrails.

Related science terms

  • 飽和(ほうわ): saturation — the baseline state for comparison.
  • 不飽和(ふほうわ): unsaturated — below the saturation point.
  • 結晶化(けっしょうか): crystallization — what happens when a supersaturated solution is disturbed.
  • 溶解度(ようかいど): solubility — the maximum amount of a substance that dissolves at a given temperature.
  • 核生成(かくせいせい): nucleation — the triggering of crystal formation.

Usage

In essays and journalism the word is occasionally used metaphorically, as in 情報(じょうほう)過飽和(かほうわ) (information supersaturation) or 過飽和(かほうわ)市場(しじょう) (a market already overflowing with similar products). These uses are stylistically marked.

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Technical and written. Primarily at home in science textbooks, research papers, and educational materials.

Related Words

Related: 結晶化(けっしょうか) (crystallization)
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Added 2026.4.12 6:32 · Revised 2026.9.2 13:02
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