DirectX 11 (or DX11) is a set of drivers distributed by Microsoft that offer improved visual and audio performance. Its main function, and the one for which it is best known, is allow you to run games with excellent state of the art graphics in video games.
A reprimand is a severe, formal or official reproof. Reprimanding takes in different forms in different legal systems. A reprimand may be a formal legal action issued by a government agency or professional governing board (e.g. medical board, bar council). It may also be an administrative warning issued by an employer or school.
A reproof is a negative comment, reprimand, or rebuke. Even the nicest kindergarten teacher in the world will give his students a reproof if they won't stop laughing and running around the classroom.