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coast [coast 词源字典]: coast: [13] Latin costa meant ‘rib’ (hence the English medical term intercostal ‘between the ribs’), but also more generally ‘flank, side’. It was in this sense that it passed into Old French as coste, and subsequently into English. The modern meaning ‘seashore’ (which had already developed in Old French) arises from the shore being thought of as the ‘side’ or ‘edge’ of the land (compare seaside).

Amongst the senses of the French word little represented in English is ‘hillside, slope’; it was however adopted in North America for a ‘slope down which one slides on a sledge’, and came to be used in the mid 19th century as a verb meaning ‘sledge down such a slope’. That was the source of the modern verbal sense ‘freewheel’. The coster of costermonger [16] was originally costard, a variety of apple named from its prominent ‘ribs’.

And another hidden relative is cutlet [18], borrowed from French côtelette, literally ‘little rib’.
=> costermonger, cutlet, intercostal[coast etymology, coast origin, 英语词源]
free-wheeling (adj.): also freewheeling, 1903, from free wheel (1899, see free (adj.) + wheel (n.)); a bicycle wheel that turns even when not being pedaled, later from the name of a kind of automobile drive system that allowed cars to coast without being slowed by the engine. Figurative sense is from 1911.