What does diffusible mean?
Diffusible is an adjective describing something that can diffuse — that is, spread or scatter from an area of higher concentration to one of lower concentration, typically through air, liquid, or a membrane. It belongs chiefly to the vocabulary of science: physiologists speak of diffusible gases crossing the alveolar wall, chemists of diffusible ions moving through solution, and pharmacologists of whether a drug is diffusible enough to reach its target tissue. A substance described as diffusible need not be moving at any given moment; the word captures a capacity or property rather than an action, which is why phrases like "highly diffusible" and "readily diffusible" are common. Though technical in register, the word is transparent once its root, the Latin diffundere (to pour out or spread), is recognized, making it a useful term for anyone reading about how substances travel through living systems or materials.
adjectiveCapable of diffusing or of being diffused; able to spread or scatter readily, especially through a medium by natural movement.
- Capable of diffusing or being diffused, especially through a medium such as a membrane or gas — the dominant scientific and medical sense.
- (Less common) Tending to spread out or scatter readily in general contexts.
"Oxygen is highly diffusible across the thin membranes of the lung's alveoli."
"The dye remained diffusible throughout the gel, spreading evenly within minutes."
"Because carbon dioxide is more diffusible than oxygen, it crosses cell membranes with ease."
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of diffusible
Diffusible derives from the Latin verb diffundere, meaning "to pour out, spread abroad," formed from dis- (apart) plus fundere (to pour). English adopted it in the early modern period alongside the related words diffuse and diffusion, all built on the same Latin root. Its closest cognates include effusive and profuse, which likewise descend from fundere with different prefixes. The suffix -able marks it as expressing capability, giving the sense "able to be diffused."
Related word forms
How diffusible is actually used
Predominantly a technical term found in physiology, chemistry, pharmacology, and materials science; rare in everyday speech. In medicine it often appears in discussions of how gases, drugs, or ions pass across membranes. The comparative "more diffusible" is standard rather than "diffusibler."
Easily confused with diffusible
"Diffusible" describes something capable of being diffused, while "diffusive" describes something that tends to cause diffusion or spread itself widely.
"Effusive" means pouring out freely or expressing emotion unrestrainedly, whereas "diffusible" concerns the capacity to spread through a medium.