Han ideograph 柧

柧 names a corner or ridge, especially an edge on faceted wood.

The graph combines 木, the wood component, with 瓜 as a sound-bearing part. A form attributed to manuscripts from the ancient state of Chu is placed before the seal-script form recorded in Shuowen, an early Chinese dictionary. Seal script is an older formal style of Chinese writing.

柧棱 extends the concrete sense: it names the turning ridge at the top of a palace roof and can describe someone's conspicuous talent or sharpness. Japanese records also preserve the roof-corner sense as an uncommon architectural term. A Shuowen commentary says 觚 displaced 柧; the characters are historically connected.

What does 柧 mean when someone sends it alone?

By itself, 柧 gives no reliable clue to the sender’s tone.

Its dictionary sense is a corner or ridge, but the reason someone sent it and the tone they intend depend on the surrounding words. In a work message, add a phrase that makes your meaning clear.