Simple Definition:

Cognitive refers to the mental processes and activities related to thinking, understanding, learning, and remembering [processing information in our minds]. It involves the use of memory, attention, perception, problem-solving, and language skills. For example, when you solve a math problem, understand a story, or memorize a phone number, you are using your cognitive abilities.

Very Simple Definition:

Cognitive refers to how our brain thinks, learns, and remembers things. For example, when you solve a math problem, understand a story, or memorize a phone number, you are using your cognitive abilities.