Common loanword used in contexts like secret information, secret items, or secret events. Often appears in compound nouns.
これは会社のシークレット情報です。
This is the company's secret information.
彼女はシークレットシューズを履いている。
She is wearing secret shoes (height-increasing insoles).
They're keeping their marriage a secret for now.
The release date of the new product is a secret.