Which term describes quantities fully described only by magnitude?

The term that describes quantities fully characterized only by magnitude is scalars. Scalars are defined by a single numerical value along with a unit of measurement, which indicates how much of a quantity there is, such as temperature, mass, or time. These quantities do not have a direction associated with them; they solely represent a size or amount.

In contrast, vectors are quantities that require both magnitude and direction to be fully described. For example, velocity and displacement are vectors, as they indicate not only how fast something is moving or how far it has gone but also in which direction.

Forces and acceleration are specific types of vectors. A force has both a magnitude (the amount of push or pull) and a direction, and similarly, acceleration indicates how quickly the velocity of an object is changing in a particular direction. Therefore, these quantities cannot be classified as scalars since their descriptions encompass both size and direction.