n. Mathematics A quantity, such as velocity, completely specified by a magnitude and a direction.n. Mathematics A one-dimensional array.n. Mathematics An element of a vector space.n. Pathology An organism, such as a mosquito or tick, that carries disease-causing microorganisms from one host to another.n. Genetics A bacteriophage, plasmid, or other agent that transfers genetic material from one cell to another.n. A force or influence.n. A course or direction, as of an airplane.v. To guide (a pilot or aircraft, for example) by means of radio communication according to vectors.