indescribable
adjective uk/ˌɪn.dɪˈskraɪ.bə.bəl/ us/ˌɪn.dɪˈskraɪ.bə.bəl/
难以形容的;不可名状的
impossible to describe, especially because of being extremely good or bad
a scene of indescribable beauty 无法形容的美景
The pain was indescribable. 疼痛难以言表。