Ad*her"ence (&?;), n. [Cf. F. adhérence, LL. adhaerentia.] 1. The quality or state of adhering.

2. The state of being fixed in attachment; fidelity; steady attachment; adhesion; as, adherence to a party or to opinions.

Syn. -- Adherence, Adhesion. These words, which were once freely interchanged, are now almost entirely separated. Adherence is no longer used to denote physical union, but is applied, to mental states or habits; as, a strict adherence to one's duty; close adherence to the argument, etc. Adhesion is now confined chiefly to the physical sense, except in the phrase "To give in one's adhesion to a cause or a party."

• The close physical union of two objects
  
• Faithful support for some cause
  
• (medical) The extent to which a patient continues an agreed treatment plan