Merriam-Webster's Collegiate® Dictionary, 11th Edition
COAST
I. noun
Etymology: Middle English cost, from Anglo-French coste, from Latin costa rib, side; akin to Old Church Slavic kostĭ bone
Date: 14th century
the land near a shore ; seashore , border , frontier ,
3. a hill or slope suited to coasting, a slide down a slope (as on a sled), the Pacific coast of the United States, the immediate area of view, coastal adjective coastwise adverb or adjective
II. verb
Date: 14th century
transitive verb to move along or past the side of ; skirt , to sail along the shore of, intransitive verb
1. to travel on land along a coast or along or past the side of something, to sail along the shore,
2. to slide, run, or glide downhill by the force of gravity, to move along without or as if without further application of propulsive power (as by momentum or gravity), to proceed easily without special application of effort or concern