noun

1. Obsolete an animal's spine or back
2. the long, narrow top or crest of something, as of an animal's back, a wave, a mountain, etc.
3. a long, narrow elevation of land or a similar range of hills or mountains
4. any raised line or raised narrow strip, as in corded fabric, plowed land, etc.
5. the horizontal line formed by the meeting of two sloping surfaces the ridge of a roof
6. a long, narrow high-pressure area on a weather map

Etymology: ME rigge < OE hrycg, akin to ON hrygr, backbone, Ger rücken, back < IE *(s)kreuk-, a hump, mound < base *(s)ker-, to bend > L curvus, bent, circus, a ring

transitive verb, intransitive verb ridged, ridging ridg′·ing

1. to mark or be marked with a ridge or ridges
2. to form into or furnish with a ridge or ridges