Vector

From Latin vector ("carrier"), from vehÅ ("I carry, I bear").

The "person or entity that passes along an urban legend or other meme" sense derives from the disease sense.

Full definition of vector

(plural vectors)

(mathematics) A directed quantity, one with both magnitude and direction; the signed difference between two points.

1914, S:The New Student's Reference Work/Vector, As examples of vector quantities may be mentioned the distance between any two given points, a velocity, a force, an acceleration, angular velocity, intensity of magnetization flux of heat.

(mathematics) An ordered tuple representing a directed quantity or the between two points.
(mathematics) Any member of a (generalized) vector space.''The vectors in ${\mathbb Q} X$ are the single-variable polynomials with rational coefficients: one is

x^{42}+\frac1{137}x-1.''

(aviation) A chosen course or direction for motion, as of an aircraft.
(carrier of a disease-causing agent)(epidemiology) A carrier of a disease-causing agent.
(sociology) A person or entity that passes along an urban legend or other meme.
(psychology) A recurring psychosocial issue that stimulates growth and development in the personality.
The way in which the eyes are drawn across the visual text. The trail that a book cover can encourage the eyes to follow from certain objects to others.
(computing, operating systems) A memory address containing the address of a code entry point, usually one which is part of a table and often one that is dereferenced and jumped to during the execution of an interrupt.
(programming) A one-dimensional array.

(programming) The term vector is used loosely when the indices are not (either positive or non-negative) integers.

1994, Eve Kosofsky Sedgwick, Tendencies...if love is vectored toward an object and Elinor's here flies toward Marianne, Marianne's in turn toward Willoughby.