thumbholes是thumbhole的复数
thumbhole
美 
英 
- 网络塞拇指的孔;供塞入拇指的孔;指孔
 
复数:thumbholes  
n.  | 1. a hole in something such as a bowling ball into which a thumb can be inserted in order to provide a grip 2. a hole in a wind instrument that is covered and uncovered by the thumb to produce notes  |