Definition of "dolphin"

At each end of the piers in the water, in cases where several rows of pile are driven, a sort of cutwater should be formed, in order to ward off heavy bodies, such as floating trees, ice, etc. and prevent them from injuring the superstructure (called in German constructions, "Eisbrecher," or ice-breaker). This is usually done by driving one pile by itself in advance of the rest, or by forming what is called a "dolphin" at each end of the pier.

1844, The Technical Educator, an encyclopædia, page 107

An ice-breaker or dolphin was also constructed during the latter part of the autumn, a little above the site for No. 2 dam, or that for the twoer nearest the Pesth shore; this dolphin, which served as a protection against the ice, rafts, &c. was constructed at this time, so that a means might be afforded of judging of the actual force of the ice during the winter ensuing; and the event proved that its construction was most fortunate, as the winter of 1840-41 was unusually severe.

1852, William Tierney Clark, An Account, with illustrations, of the Suspension Bridge across the River Danube, uniting Pesth with Buda and the adjacent country, in the Kingdom of Hungary, etc, page 37

The Dolphin is now seldom used, but a rope treated in the same manner, with mousings raised on it at regular intervals, is sometimes put around a Launch, just below the gunwale outside and secured there as a sort of permanent fender; this also is called a Dolphin.

1868, Stephen Bleecker Luce, Seamanship, page 28

For a dolphin or buoy to be placed on the south point of Goat Island, in the harbor of Newport, one hundred and fifty dollars.

1852, The Congressional Globe: Volume 32, page xxx

Sometimes a stoppage would take place owing to the accumulation of ice between the Dolphin and the dam, which kept that above back until a mass of ice more resembling an island than anything else it can be compared to, would force the whole mass before it, breaking up the large blocks accumulated at the dam into a thousand pieces.

1860 March 31, “Victoria Bridge”, in American Railroad Journal, volume 16, number 13