Answer:
magnitude
Explanation:
There are two types of quantities.
Scalars: The quantities which are completely described by their magnitudes only are called scalars.
For example, mass, length, time, speed, temperature, etc.
Vectors: The quantities which are completely explained by their magnitude and direction both are called vectors. For example, velocity, weight, force, momentum, etc.
As speed is a scalar quantity so it can be completely described by their magnitude only.