What is the term for a sharp tool used for hair cutting?

The correct term for a sharp tool used for hair cutting is a razor. Razors are specifically designed with a keen edge that allows for precise cutting and shaping of hair, making them ideal for tasks such as shaving and creating detailed lines. The design and sharpness of a razor enable barbers to achieve close cuts, which is often necessary for certain styles and for the clean shaving of facial hair.

Razors are distinct from scissors and clippers, which serve different purposes in hair cutting. While scissors are also sharp tools and can be used for cutting hair, they operate differently and are typically employed for more versatile cutting techniques and textures. Clippers, on the other hand, are electric devices that help to quickly shorten hair and are not sharp in the same sense as a razor, lacking the fine edge necessary for precise cutting.

A comb is not a cutting tool but rather a styling and detangling instrument used to organize hair strands before cutting or styling. Thus, the focus on the sharpness and specific function of a razor makes it the correct answer in this context.