a long narrow hilltop, mountain range, or watershed:

山の背; 分水嶺

e.g. the northeast ridge of Everest.

the line or edge formed where the two sloping sides of a roof meet at the top.

Meteorology an elongated region of high atmospheric pressure.

〘気象〙 (天気図で)高気圧の張出し部

a narrow raised band running along or across a surface:

(表面の細長い)隆起部; 尾根, (屋根の)棟; (動物の)背, 背すじ; (靴底の)刻み目

e.g. buff your nails in order to smooth ridges.

a raised strip of arable land, especially (in medieval open fields) one of a set separated by furrows.

畝

verb with object (often as adjective ridged)

mark with or form into narrow raised bands:

…を隆起させる

e.g. the ridged sand of the beach.

no object (of a surface) form into or rise up as a narrow raised band:

畝をなす, (畝状に)隆起する

e.g. the crust of the earth ridged.

form (arable land) into raised strips separated by furrows:

…に棟［畝］を付ける

e.g. a field plowed in narrow stretches that are ridged up slightly.

ridgy |ˈrijē| adjective

Old English hrycg‘spine, crest’, of Germanic origin; related to Dutch rug and German Rücken ‘back’.