minim rest

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun music A minim rest is a pause or interval of silence equal in duration to two quarter rests or one half of a whole rest. In common or 4/4 time, its duration is two beats.
• noun music A symbol used in musical notation drawn as a solid rectangle directly above the middle line of a staff whose height is half the distance between lines.