hunger, thirst
饑 centers on a severe lack of essential sustenance: hunger for food and thirst for water. Both meanings express a pressing bodily need.
饑 combines 飠 (food/eat) with 幾, which likely contributes the sound and may suggest a sense of scarcity or smallness. The character expresses hunger or thirst through the idea of lacking food or drink.
The food radical 飠 on the left shows the body's need, and the complex right side 幾 looks like a person weakened by emptiness. Picture someone so hungry and thirsty that even the thought of food makes them feel faint.
For キ, imagine a key (キー) that unlocks a pantry full of food when you are starving. The key -> キ sound helps you remember the reading while the hunger drives the scene.
hungry