I was wondering the other day about these two words.

Problem:
The two words mean exactly the same thing, but people don’t use one or the other consistently.

Explanation:
As defined by Wikipedia, “resilience” means the property of a material to absorb energy when it is deformed elastically.

Wikipedia automatically redirects to the “resilience” page when a visitor puts “resiliency” in the search box and clicks the [Go] button.

Similarly, Dictionary.com defines “resiliency” as resilience.

For fun, I searched Google for each of the following words (without the quotation marks) and got about the indicated numbers of matches:

• “resilience” — 12,800,000 matches
• “resiliency” — 3,770,000 matches

This tells me that Web authors favor “resilience” over “resiliency” by a ratio of 3.40:1.

Solution:
Use “resilience” instead of “resiliency” because the latter is more difficult to say and to be understood and because it means the former.