A vimpa (plural: vimpae) is a veil or shawl worn over the shoulders of servers who carry the mitre and crosier during liturgical functions when they are not being used by the bishop, in the Roman Catholic, Anglican, and some other western churches.
The vimpa is used to hold the mitre or crosier, thus preventing direct contact with the pontificalia by anyone other than the bishop. The two vimpa-bearers attend the bishop during Pontifical Mass, and follow him in procession. Their function is to show the congregation that the person carrying the item (either the Mitre or the Crozier) does not have the authority of a bishop. For the same reason, the carrier of the Crozier also holds it in the closed position, and in the right hand i.e. crook facing towards them, in contrast to the bishop, who holds it with the crook facing away from himself, in the left hand.
The vimpa may take the form of a cape-like shawl or a many-pleated scarf, with a base colour usually of either white or silver. A vimpa can be a simple white/silver veil or can be fashioned with one or many liturgical symbols, such as crosses. The vimpa can hang on the mitre- and crosier-bearers' shoulders or be secured in the front by velcro, ribbon or even clasps. They can end as short as the server's waist, and as long as the server's feet.
Due to its form, many people often mistake the vimpa for a Humeral Veil which is used to hold the Monstrance. There is nothing wrong with a vimpa being fashioned like a humeral veil as long as it is not overdone and follows important rules such as colour and design. Since it is only used at Pontifical Masses, a well-fashioned vimpa can stand out in the grandness of the celebration and appear spectacular when holding a mitre and crosier.
The term is also used to refer to the attendants themselves, when the plural form vimpas is usually used. The term 'vimpa-boys' is sometimes heard, being derived from the historical fact that in many churches the altar servers (and therefore the vimpa-bearers) were young boys. A vimpa is occasionally used in the Anglican liturgy in an alternative function, when the crosier is carried before the bishop in procession, often by a junior Clerk in Holy Orders.