heart, standing heart radical variant (no. 61)
忄 is the standing heart radical, used as a left-side component in characters related to emotions, thoughts, and mental states. Its core meaning is 'heart' in the figurative sense of inner feeling.
忄 is a variant form of 心 (heart) used as a left-side radical. It originated as a cursive simplification of 心, adapting its shape to fit vertically in compound characters.
The three strokes of 忄 look like a simplified heart shape turned on its side, with the left stroke as the aorta and the two right strokes as the ventricles. Picture it as a compact, standing heart ready to be filled with emotion.
For シン, imagine a shin (shin bone) that feels a heartbeat when you press it: shin -> シン, and the standing heart radical 忄 pulses with life.