可言 Words — Dong Chinese Dictionary

kěyán

to speak of

妙不可言 miàobùkěyán indescribable

too wonderful for words
不可言喻 bùkěyányù inexpressible

inexpressible; beyond words (idiom)
只可意会，不可言传 zhǐkěyìhuì, bùkěyánchuán ineffable

can be understood, but not described; mysterious and subtle
可以意会，不可言传 kěyǐyìhuì, bùkěyánchuán ineffable

can be understood, but not described (idiom, from Zhuangzi); mysterious and subtle