There are many definitions for the word priesthood. But in Catholic Church priest is one who offer the sacrifice of the Mass. It is very important that the sacrifice of the Mass be offered from every altars around the world until the end of time. Therefore it is important to pray for the priest and below is a wonderful prayer by St. Therese of Lisieux.
O Jesus, eternal Priest,
keep your priests within the shelter of Your Sacred Heart, where none may touch them.
Keep unstained their anointed hands,
which daily touch Your Sacred Body.
Keep unsullied their lips,
daily purpled with your Precious Blood.
Keep pure and unearthly their hearts,
sealed with the sublime mark of the priesthood.
Let Your holy love surround them and
shield them from the world’s contagion.
Bless their labors with abundant fruit and
may the souls to whom they minister be their joy and consolation here and in heaven their beautiful and
everlasting crown. Amen.