ineffable       
adjective  formal uk/ɪˈnef.ə.bəl/ us/ˌɪnˈef.ə.bəl/
 (尤指喜悦)言语难以表达的,不可言喻的
causing so much emotion, especially pleasure, that it cannot be described
  ineffable joy/beauty 难以言表的喜悦/美丽 
 
英汉双解词典收录81607条英汉双解翻译词条,基本涵盖了全部常用单词的读音、翻译及用法,是英语学习的有利工具。