軟

Originally written 輭, a phono-semantic compound (形聲 /形声, OC *njonʔ): semantic 車 (“carriage”) + phonetic 耎 (OC *njonʔ). 耎 turned into 欠 over time due to a popular variant.

The meaning of the carriage is not fully clear. It could be linked to the synonym 柔, which indicates the wood soft enough to be cut, or it could indicate the concept of being tired and weak after dragging a heavy carriage, hence "soft"; the right component could add part of the meaning, since it originally depicts a man under the rain, hence getting soaked (perhaps while dragging a heavy carriage). The modern component 欠 depicts a man kneeling with an open mouth, perhaps while breathing due to exhaustion.

Probably cognate with 柔 (OC *mlju, “soft”), see there for more (STEDT).