thumb·nail
noun/ˈθʌmneɪl/
/ˈθʌmneɪl/
- the nail on the thumb
拇指指甲 - (also thumbnail image)(computing) a very small picture on a computer screen that shows you what a larger picture looks like, or what a page of a document will look like when you print it
索引图像；（打印预览）缩略图