what age is considered a senior?

As of 2/20/19, that age is 62. Here is the link to the FAQ: https://www.cinemark.com/faq-tickets-purchases-refunds

Cinemark senior age is 62, I found this on Cinemark's Frequently Asked Questions.

65 years old or older. You would need to show a Photo ID with your DOB.

65.. you need the senior citizen card