Origin

This character combines heart (心) at the bottom, which classifies it as being about emotional or physical suffering, with a sound component (串) at the top that hints at how it's pronounced. The heart radical makes sense because illness and affliction were understood as conditions affecting the heart or inner self. By pairing the meaning-bearing heart symbol with a phonetic guide, the character efficiently conveys both what it means — to be sick or troubled — and roughly how to say it.