A key forming part of the Morse telegraph apparatus, which is pressed and released to send signals in Morse code.
Mid 19th century; earliest use found in George Prescott (1830–1894).
英语词典包含464360条英英释义在线翻译词条，基本涵盖了全部常用单词的英英翻译及用法，是英语学习的有利工具。