What is Singular?

Legal Definition
Construction. In grammar the singular is used to express only one,

not plural. Johnson.

2. In law, the singular frequently includes the plural. A bequest to "my nearest relation," for example, will be considered as a bequest to all the relations in the same degree, who are nearest to the testator. 1 Ves. sen. 337; 1 Bro. C. C. 293. A bequest made to "my heir," by a person who had three heirs, will be construed in the plural. 4 Russ. C. C. 384.

3. The same rule obtains in the civil law: In usu juris frequenter uti nos singulari appellationie, am plura significari vellemus. Dig. 50, l6, 158.
-- Bouviers Law Dictionary
Legal Definition
Each; as in the expression "all and singular." Also, individual. As to singular "Successor," and "Title," see those titles.
-- Black's Law Dictionary