He was charged with a secret mission.

Let's keep this a secret.

The spy had to secrete the confidential documents before the enemy arrived.

The endocrine gland secretes hormones into the bloodstream.

The secretion of hormones is an important process in the body.

He is very secretive about his personal life.

The secret agent infiltrated the enemy's headquarters.

The secret service is responsible for protecting the president and investigating counterfeit money.

The documents containing top-secret information were stored in a secure vault.