Origin

The character combines a heart or mind radical on the left, which indicates this word relates to thoughts and feelings, with the component 真 (meaning "true" or "real") on the right, which serves as a sound hint for the pronunciation シン. The idea is that a careful, prudent mind is one that seeks truth and acts with genuine sincerity rather than carelessness. Over time, the character came to mean being cautious and discreet — the kind of thoughtful restraint that comes from taking things seriously and checking yourself before you act.