When we attend church, what precisely defines “worship”?
The essence of
worship is sacrifice.
The praising, singing, petitioning, and adoration of God is
in addition to the worship of God, which is the offering of sacrifice to Him.
In Old Testament times, they sacrificed animals of all kinds, grains, fruits, drinks, and all sorts of stuff.
The Sacrifice of the Mass is the Eucharist - the bread and wine offered to God by the priest, which is then accepted by God and exchanged for the Body and Blood of Christ, which precisely displaces the bread and wine (which is now in Heaven with God).
There are also offerings of incense, money, and praise, as well, but the main thing is the offering of the bread and wine, which is then exchanged for Christ’s perfect Sacrifice of Himself on the Cross.
I do not know what (if anything) Protestants sacrifice in their Sunday gatherings.
Should we call the Catholic Mass a “worship” event?
Indeed, it is the only thing I know of that could safely be referred to in that way, since it’s the only Christian celebration I know of that actually incorporates the most essential element of worship, which is sacrifice.