Worship Is
Our church just finished a month-long sermon series on the church and worship, and this was the definition of worship we used:
“Worship is the fitting and delightful response of God’s people to him, our Creator and Redeemer, for what he has done, for his glory in creation and redemption, through Christ, by the power and direction of Jesus himself through his Holy Spirit.”
It relies on the definitions provided by Gibson (Reformational and dogmatic) and Block (biblical-theological) in this wonderful little list.