An Etymological Dictionary of Astronomy and Astrophysics

1. The act or state of adhering; state of being adhered or united.
   

2. Steady or devoted attachment, support, etc.; adherence.
   

3. Physics: The molecular force of attraction in the area of contact between unlike bodies that acts to hold them together (Dictionary.com). See also → cohesion.

See also: Verbal noun from → adhere; → -tion.