Final answer:
In haircutting, a 90 degree elevation means holding the hair out from the head at a right angle during cutting, leading to a uniform layer and balanced shape.
Step-by-step explanation:
In the context of haircutting, a 90 degree elevation refers to the angle at which the hair is held or lifted from the head when cutting. Specifically, it means that the hair being cut is held out from the head at a right angle, parallel to the floor, which typically results in a uniform layer throughout the haircut. This technique is used by stylists to create a balanced shape with equal weight distribution, often seen in classic layered cuts. When the hair is cut at a 90 degree elevation, each section of hair is at the same distance from the scalp, producing an even and consistent length after the cut.