syncline
noun /ˈsɪŋklaɪn/
/ˈsɪŋklaɪn/
(geology- an area of ground where layers of rock in the earth’s surface have been folded into a curve that is lower in the middle than at the ends
compare anticline向斜 词源late 19th cent.: from syn- ‘together’ + Greek klinein ‘to lean’, on the pattern of incline.