Definition of "insular"

At the time of the arrival of the Tonquin he had about forty schooners, of from twenty to thirty tons burthen, and one old American ship. With these he held undisputed sway over his insular domains, and carried on intercourse with the chiefs or governors whom he had placed in command of the several islands.

1836 October, Washington Irving, chapter VI, in Astoria, or Anecdotes of an Enterprise beyond the Rocky Mountains. […], volume I, Philadelphia, Pa.: [Henry Charles] Carey, [Isaac] Lea, & Blanchard, page 67

There now is your insular city of the Manhattoes, belted round by wharves as Indian isles by coral reefs.

1851 November 14, Herman Melville, chapter I, in Moby-Dick; or, The Whale, 1st American edition, New York, N.Y.: Harper & Brothers; London: Richard Bentley

During the four years since his puppyhood he had lived the life of a sated aristocrat; he had a fine pride in himself, was even a trifle egotistical, as country gentlemen sometimes become because of their insular situation.

1903 July, Jack London, “Into the Primitive”, in The Call of the Wild, New York, N.Y.: The Macmillan Company; London: Macmillan & Co., pages 18–19

Harriet was fretful and insular. Miss Abbott was pleasant, and insisted on praising everything: her only regret was that she had no pretty clothes with her.

1905, E[dward] M[organ] Forster, chapter VI, in Where Angels Fear to Tread, Edinburgh, London: William Blackwood and Sons, page 202

these insulars in general live in a gross saline air , and their vessels being less elastic are consequently less able to subdue and cast off what their bodies as sponges draw in

1744, George Berkeley, Siris, a chain of philosophical reflections and inquiries, concerning the virtues of tar-water