fear, be afraid
惴 centers on a state of anxious fear or being afraid, often with a sense of trembling or unease.
惴 combines 忄 (heart/mind) with 耑, which likely contributes a phonetic element. The heart radical suggests an emotion, fitting the meaning of fear.
The heart radical 忄 beside 耑 suggests a heart gripped by fear. Imagine your heart pounding when you see something frightening.
For ズイ, picture a zoo where you feel afraid: zoo -> ズイ, and your heart races with fear.