adhesion

UK: /ədˈhiːʒ^ən/ US: /ædˈhiʒən/ ,(ad hē′zhən)

WordReference Random House Learner's Dictionary of American English © 2025

ad•he•sion /ædˈhiʒən/   n. [uncountable]

1. the act, state, or quality of adhering.

WordReference Random House Unabridged Dictionary of American English © 2025

ad•he•sion  (ad hē′zhən), n. 

1. the act or state of adhering;
   state of being adhered or united:
   the adhesion of parts united by growth.
2. steady or devoted attachment, support, etc.;
   adherence.
3. assent;
   concurrence.
4. Physics the molecular force of attraction in the area of contact between unlike bodies that acts to hold them together. Cf. cohesion (def. 2).
5. Pathology
   • the abnormal union of adjacent tissues.
   • the tissue involved.
6. Botany the union of normally separate parts.
7. Rail Transport
   • the frictional resistance of rails to the tendency of driving wheels to slip.
   • See factor of adhesion. 

• Medieval Latin adhēsiōn- for Latin adhaesiōn- (stem of adhaesiō) a clinging, equivalent. to adhaes(us), past participle of adhaerēre to adhere + -iōn- -ion
• 1615–25

ad•he′sion•al, adj. 

Collins Concise English Dictionary © HarperCollins Publishers::

adhesion / ədˈhiːʒən/ noun

1. the quality or condition of sticking together or holding fast
2. ability to make firm contact without skidding or slipping
3. attachment or fidelity, as to a political party, cause, etc
4. an attraction or repulsion between the molecules of unlike substances in contact: distinguished from cohesion
5. abnormal union of structures or parts

Etymology: 17th Century: from Latin adhaesiōn- a sticking. See adhereUSAGE
Adhesion is the preferred term when talking about sticking or holding fast in a physical sense. Adherence is preferred when talking about attachment to a political party, cause, etc