Definition - What does Kantha Kupa mean?
Kantha kupa is the pit of the throat and is a focal point used in Patanjali's samyama meditation to control thirst and hunger. Thirst and hunger can distract from the focus of meditation or interrupt it entirely when a yogi takes a break to eat. Breaks like these create discomfort as food digests. When a yogi learns how to control thirst and hunger, they are able to meditate for longer periods of time and receive more benefits from their practice.
Yogapedia explains Kantha Kupa
Located at the base of the throat, the kantha kupa is one of the areas of the body that the yogi can mindfully engage to control thirst and hunger. Meditating on the kantha kupa allows a yogi to develop sthairyam, or "steadfastness," in the physical body and in the mind. Learning how to understand the sensations generated in the kantha kupa brings more awareness to the yogi when they do eat and drink and allows for differentiation from hunger and appetite.
The samyama meditation on the kantha kupa controls thirst and hunger, the meditation uses the mantra: Kantakoope Ksut Pipaasaa Nivrttih, which translates to "throat hunger thirst overcome." Overtime, the yogi will develop control of thoughts, of thirst and hunger and will be able to meditate for longer periods of time. In Patanjali's meditation, awareness is directed to the kantha kupa with great concentration and uninterrupted attention until the yogi loses self-awareness and achieves samadhi.