Definitions:

1. an expression of gratitude noun
   • They expressed their appreciation in a short note.
2. an increase in price or value noun
   • an appreciation of 30% in the value of real estate
3. delicate discrimination, especially of aesthetic values noun
   • I have an appreciation of the fine arts.

Synonyms:

• admiration
• discernment
• grasp
• hold
• perceptiveness
• taste