A person or thing to be treated in a specified way.
[Latin verb forms -andus, -anda, and -andum, which function as adjectives.]
Words usually have a passive sense of something or somebody which is to suffer some action. A multiplicand (Latin multiplicandus, to be multiplied) is a quantity which is to be multiplied by another; an operand (Latin operandum, on which labour is to be expended) is a quantity on which a mathematical operation is to be carried out; an ordinand (Latin ordinandus, being put in order) is a person under training to be ordained as a priest or minister.
A small number of modern technical terms have been created using -and: analysand (from analyse), a person undergoing psychoanalysis, ligand (Latin ligandus, that can be tied), an ion or molecule attached to a metal atom by coordinate bonding, and proband (Latin probandus, to be proved), a person serving as the starting point for the genetic study of a family.