I. Basic Concepts

1. Adhesion: The state in which two surfaces are bonded together by chemical forces, physical forces, or a combination of both. Synonym: adherence.
2. Cohesion: The state in which the particles within a single substance are bound together by primary valence forces and secondary valence forces.
3. Mechanical Adhesion: The bond generated by the interlocking action of an adhesive between two surfaces. Synonym: mechanical adherence.
4. Adhesive Failure: The visually observable failure phenomenon that occurs at the interface between the adhesive and the adherend.
5. Cohesive Failure: The visually observable failure phenomenon that occurs within the adhesive or the adherend.
6. Compatibility: The ability of two or more substances to have mutual affinity when mixed.
7. Adhesive: A substance that can bond adherends together through the action of adhesion.
8. Adherend: An object that is ready to be bonded or the objects on both sides of the adhesive layer after bonding.
9. Substrate: The material used for applying the adhesive on its surface. Note: This is a more general term than "adherend".
10. Wetting: The affinity of a liquid for a solid. The smaller the contact angle between them, the easier it is for the solid surface to be wetted by the liquid. Synonym: moistening.
11. Dry: The process of reducing solvents or dispersion media through evaporation or absorption to change the physical state of the adhesive on the adherend.
12. Bond: To connect the surfaces of adherends together using an adhesive. Synonym: adhesion.
13. Curing: The process by which an adhesive obtains and improves properties such as bonding strength through chemical reactions (polymerization, cross-linking, etc.).
14. Setting: The process by which an adhesive obtains and improves properties such as bonding strength and cohesive strength through chemical reactions or physical actions (such as polymerization reactions, oxidation reactions, gelation, hydration, cooling, evaporation of volatile components, etc.).
15. Adhesive Layer: The layer of adhesive in a bonded assembly.
16. Crosslinking: The process of forming chemical bonds between molecules and creating a three-dimensional network structure.
17. Delamination: The separation between layers in a laminated product caused by the failure of the adhesive, the adherend, or their interface.
18. Squeeze-out: The adhesive that is squeezed out from the adhesive layer after applying pressure to the assembly.
19. Blocking: An undesired adhesion phenomenon that occurs between materials.
20. Dry Tack (Aggressive Tack): A characteristic of certain adhesives (especially non-vulcanized rubber-based adhesives). When the volatile components in the adhesive have evaporated to a certain extent and it feels dry to the touch, it will adhere to itself upon contact.
21. Fillet: The part of the adhesive that fills the corner where two adherends meet (for example, the rounded adhesive corner formed at the end of a honeycomb core when it is bonded to the facing material).
22. Degree of Cure: The degree of chemical reaction represented during the curing of an adhesive.
23. Ageing: The phenomenon in which the properties of a bonded assembly change over time.
24. Tack: The property of an adhesive to form a considerable bonding strength immediately upon slight pressure after contacting the adherend.