Mathematics. a quantity possessing both magnitude and direction, represented by an arrow the direction of which indicates the direction of the quantity and the length of which is proportional to the magnitude. Compare scalar (def 4). such a quantity with the additional requirement that such quantities obey the parallelogram law of addition. such a quantity with the additional requirement that such quantities are to transform in a particular way under changes of the coordinate system. any generalization of the above quantities.
the direction or course followed by an airplane, missile, or the like.
Biology. an insect or other organism that transmits a pathogenic fungus, virus, bacterium, etc. any agent that acts as a carrier or transporter, as a virus or plasmid that conveys a genetically engineered DNA segment into a host cell.
Computers. an array of data ordered such that individual items can be located with a single index or subscript.
Aeronautics. to guide (an aircraft) in flight by issuing appropriate headings.