Simchah means joy, gladness, mirth, or celebration. It appears about 95 times. It is the noun form of samach (to rejoice) and describes the state or experience of joy.
Simchah characterizes God's people in worship and celebration. Festivals are times of simchah. The presence of God brings simchah. Even mourning turns to simchah when God restores. Joy is not optional but integral to covenant life.