1A train of thought, a line of intellectual development.
2A facial wrinkle supposedly caused by concentrated thinking.
Mid 19th century; earliest use found in Martin Tupper (1810–1889), poet and writer.
英汉双解词典包含464360条英汉词条，基本涵盖了全部常用单词的翻译及用法，是英语学习的有利工具。