indefinableadj.n.

1810 tr. Mad. Cottin's Chevalier de Versenai I. 194 That secret and indefinable instinct.

1822 C. Lamb Diss. Roast Pig in Elia 1st Ser. O call it not fat! but an indefinable sweetness growing up to it.

1830 I. D'Israeli Comm. Life Charles I III. xiii. 269 An obscure and indefinable line.

1863 ‘G. Eliot’ Romola II. ii. 19 Something as indefinable as the changes in the morning twilight.

1867 M. E. Braddon R. Godwin I. i. 2 Every look, every movement was instinct with that indefinable grace for which we can find no better name than good breeding.

1810 tr. Mad. Cottin's Chev. de Versenai I. 164 That woman is one of your indefinables.

1904 Mind XIII. 132 On the indefinables of philosophy, especially, much new light is thrown by M. Couturat's labours.

1927 F. A. Lindemann in R. J. S. McDowall The Mind 137 Though the so-called physical laws will be in general consistent with reality, there is no certainty that the indefinables employed in their statement..have any fundamental significance beyond their appeal to the mental preferences..of the physicist.

1927 F. A. Lindemann in R. J. S. McDowall The Mind 139 The commonest indefinables used in physics are space and time.

1932 F. A. Lindemann Physical Significance of Quantum Theory 12 The indefinables upon which all our thought processes depend.

1932 F. A. Lindemann Physical Significance of Quantum Theory 14 The three indefinables commonly used in physics are length, time, and mass.

1948 Mind 57 409 What we ignored was the less exact and less elegant work of insuring that the defining but undefined general terms upon which our explanations finally depended were themselves understood. The application of these indefinables we knew could be explained only by examples but the work of providing and arranging those examples and surrounding them with comment bringing out their interconnexions we could not bring ourselves to do.

1963 Times 26 Jan. 4/7 Halewyn declares his allegiance to evil and gallops away to his destruction; his talk is a series of verbal conjuring tricks with indefinables.

1889 Harper's Mag. Dec. 118/1 It has a vaporous indefinableness that leaves it a riddle.

1847 J. Craig New Universal Dict. Indefinably.

1849 W. M. Thackeray Pendennis II. ix The expression in Captain Costigan's eye..was..indefinably humourous.