What does adhesion mean?
Adhesion is the property or process by which two different surfaces or substances stick firmly together, as when glue bonds paper, paint grips a wall, or water clings to glass. It is chiefly a technical term, central to fields such as chemistry, materials science, and engineering, where measuring adhesion strength determines whether coatings, sealants, and composites will perform reliably. In medicine, adhesion also names bands of scar tissue that abnormally join organs or tissues after surgery or inflammation. A rarer, more formal sense denotes steadfast loyalty or adherence to a cause or belief. The word derives from Latin roots meaning 'to stick to', and it contrasts with cohesion, which describes the internal attraction among molecules of the same substance rather than between unlike ones. Precise, professional, and widely applicable, adhesion is an essential term wherever things must hold fast — physically or figuratively.
The action or property of sticking firmly to a surface or substance; molecular attraction between unlike bodies in contact.
"Sandblasting the metal improved the primer's adhesion."
Most common in technical and scientific contexts.
Steady devotion, support, or allegiance to a cause, party, or belief.
"His strict adhesion to constitutional principles defined his career."
Formal; 'adherence' is now the more usual word for this sense.
(Medicine) An abnormal union of adjacent tissues or organs, typically formed by scar tissue after surgery or inflammation.
"The surgeon had to divide the adhesions before reaching the organ."
In this medical sense, 'adhesion' commonly appears in the plural.
The plural is standard in medicine, where individual bands of scar tissue are referred to as adhesions; in the physical-science sense, the uncountable singular is normal.
"Post-operative adhesions can cause chronic abdominal pain."
Geckos can scamper up glass thanks to millions of microscopic foot hairs exploiting adhesion — a trick engineers are still trying to copy.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of adhesion
Adhesion comes from the Latin verb adhaerere, meaning 'to stick to', formed from ad- ('to, toward') plus haerere ('to stick, cling'). English adopted the word from Latin via French in the early modern period, with recorded use by the early 17th century. It shares its root with adhere, adherent, and adhesive, and is related to cohesion, which uses the same verb haerere with a different prefix.
Related word forms
How adhesion is actually used
Predominantly formal and technical in register: common in materials science, engineering, medicine, and law (as in 'contract of adhesion'). The figurative sense of loyal attachment is now less frequent than 'adherence' and may sound slightly old-fashioned.
Easily confused with adhesion
Adhesion is the attraction between unlike substances (e.g. glue and paper), while cohesion is the attraction between like molecules of the same substance.
Adherence usually refers figuratively to faithful support of rules or beliefs, whereas adhesion most often refers to the physical sticking of surfaces.