Serendipity

Leo A. Goodman, Notes on the Etymology of Serendipity and Some Related Philological Observations, in: Modern Language Notes, Vol. 76, No. 5 (May, 1961), p. 457:

The adventure of the three princes of Serendip, as described in the English version or in the De Mailli rendering and as referred to in Walpole's letter of 1754, the corresponding events in Voltaire's novel and in the Talmudic tale, the instance of Lord Shaftsbury's «accidental sagacity» described in Walpole's letter, all would suggest a meaning for Walpole's serendipity somewhat different from what now appears to be its present usage. E. Solly's definition in 1880, «looking for one thing and finding another,» is also somewhat different from present usage. At present serendipity usually means «the knack of spotting and exploiting good things encountered accidentally while searching for something else,» exemplified by «research directed toward the test of one hypothesis [yielding] a fortuitous b-product, an unexpected observation which bears upon theories not in question when the research was begun.»