It has that slimness just before the tail fin spreads out, and there are plenty of flying fish here, of course.
He climbed to the exit port and went clumsily down the exterior ladder to the tail fin.
The impulsive force in sailing can be given only by the tail feathers, like that of a darting trout by the tail fin.
In others the tail fin is unsymmetric: the backbone runs into the upper lobe, leaving the two lobes of unequal size.
The dorsal and ventral fins are often divided into two or more parts, and the tail fin is commonly distinctly forked.
Old English finn, from Proto-Germanic *finno (cf. Middle Low German vinne, Dutch vin), perhaps from Latin pinna "feather, wing" (see pin (n.)); or, less likely, from Latin spina "thorn, spine" (see spike (n.1)).
U.S. underworld slang sense of "$5 bill" is 1925, from Yiddish finif "five," from German fünf (see five) and thus unrelated. The same word had been used in England 1868 to mean "five pound note" (earlier finnip, 1839).
A five-dollar bill; five dollars: I gave my pal a fin/ It was the fin seen round the world. Where Reagan got the five bucks is a mystery
[1920s+ Underworld; fr Yiddish finif, ''five'']