Dear Word Detective: I was watching a cops-and-robbers show the other night, and one crook mentioned to another that “the coast is clear,” meaning that it was time to make their getaway. Where did this phrase come from? It sounds almost like another nautical expression, but I can’t imagine anyone referring to the whole coast of an island or continent at once. — Dave.
Good point. Of course, by the established conventions of crime shows, “the coast is clear” falls into the category of “famous last words.” It’s right up there with classic movie uh-ohs like “You guys go on ahead; I’m just gonna retie my shoes,” “I grew up eating these mushrooms” and “Look, a baby bear!” I’m sure there’s actually a room full of impossibly stylish and attractive cops employing technology that doesn’t exist to scan the crooks’ fingerprints from ten miles away. And they’ll have the crooks’ baby pictures before they’re halfway to the getaway car.
“Coast” is an unusually interesting word. For instance, we all know what’s meant by, say, “Barry moved to the West Coast.” But how, if at all, is that “coast” related to “Barry took his car out of gear and let it coast down the hill”? It would seem logical that the answer would be that there are two separate “coasts” in use, but they’re actually the same word.
“Coast” first appeared in Middle English (in the form “coste”), borrowed from the Old French “coste” (in modern French “côte”), which in turn was derived from the Latin “costa,” which meant “rib, flank or side” of a thing. In English in the 15th century, “coast” meant particularly the flank of a person or animal, the part protected by the ribs. The expression “by my coste” was equivalent to “by my side” (“This curdog by my coste .?will serve my sheepe to gather,” 1591).
“Coste” in Old French had also been used to mean “the edge or side of the land meeting the sea,” and English followed along and adopted this meaning too. A “coast” in English can be hundreds or thousands of miles long, but historically it can also be short stretch of “coastline” or even a small, specific place at the edge of a body of water. The phrase “the coast is clear” dates back to the 16th century and originally meant that if one were attempting a landing from the sea in hostile territory, the beach was clear of enemies. Similarly, if one were setting out from land on a mission that might meet opposition from ships, “the coast is clear” meant that enemy vessels were nowhere in evidence. “The coast is clear” was such a vivid turn of phrase that it almost immediately came into use in contexts far from any water to mean simply “the danger is over” or “there is no risk” (“With their supervisor gone for the afternoon, the coast was clear for the wastebasket basketball championships”).
Meanwhile, back in French, “côte” had also been used to mean “the side of a hill,” i.e., a slope, and in the 18th century we adopted (probably via French-speaking Canada) this sense of “coast,” but with the very specific meaning of “snow-covered slope down which one slides on a sled” (“The boys of Boston are as fond as the boys of the Revolutionary days of the coast on the Common,” 1883).
English had developed the verb “to coast” about the time that we adopted the noun, but we had always used it to mean things like “sail close to shore” or “move around the edge of something.” In the early 19th century, however, based on the “sled run” sense of the noun, we began to use “to coast” to mean “roll along on a bicycle, in a car, etc., with no power being applied, either downhill or by momentum.” By the 1930s, we were using “to coast” in a figurative sense to mean “to progress with little or no effort” (“The English team coasted comfortably to a total of 246,” 1957). So the “coast” in “the coast is clear” really is the same word as the “coasting” we do on a slow afternoon at work.