Definition of "shoal"

But that part of the coast being shoal and bare, / And rough with reefs which ran out many a mile, / His port lay on the other side o' the isle.

1819, Lord Byron, Don Juan, III.19

All told, we had scarce two miles to run; but the navigation was delicate, the entrance to this northern anchorage was not only narrow and shoal, but lay east and west, so that the schooner must be nicely handled to be got in.

1883, Robert Louis Stevenson, Treasure Island

'Twas early June, the new grass was flourishing everywheres, the posies in the yard—peonies and such—in full bloom, the sun was shining, and the water of the bay was blue, with light green streaks where the shoal showed.

1913, Joseph C. Lincoln, chapter 1, in Mr. Pratt's Patients

The god himself with ready trident stands, / And opes the deep, and spreads the moving sands, / Then heaves them off the shoals.

1697, Virgil, “Aeneis”, in John Dryden, transl., The Works of Virgil: Containing His Pastorals, Georgics, and Æneis. […], London: […] Jacob Tonson, […]

The depth of your pond should be six feet; and on the sides some shoals for the fish to sun themselves in and to lay their spawn.

1707, J[ohn] Mortimer, The Whole Art of Husbandry; or, The Way of Managing and Improving of Land. […], 2nd edition, London: […] J[ohn] H[umphreys] for H[enry] Mortlock […], and J[onathan] Robinson […], published 1708

Wolsey, that once trod the ways of glory, / And sounded all the depths and shoals of honour.

1613 (date written), William Shakespeare, [John Fletcher], “The Famous History of the Life of King Henry the Eight”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act III, scene ii]

Noting the rate at which she shoals her water - […]

1859, Matthew Fontaine Maury, Explanations and Sailing Directions to Accompany the Wind and Current Charts

great shoals of people

1625, Francis [Bacon], “Of Vicissitude of Things”, in The Essayes […], 3rd edition, London: […] Iohn Haviland for Hanna Barret

Beneath, a shoal of silver fishes glides.

c. 1661, Edmund Waller, On St. James's Park

He came directly from the shoal which we had just before entered, and in which we had struck three of his companions, as if fired with revenge for their sufferings.

1851, Herman Melville, Moby Dick