Definition of "preventive"

...and I sometimes think whether, like the ancient king, it would not be prudent to make an offering to destiny, and throw my set of emeralds into the lake." Emily could not but deprecate the emeralds being destined to any such preventive service;...

1831, L[etitia] E[lizabeth] L[andon], chapter X, in Romance and Reality. […], volume II, London: Henry Colburn and Richard Bentley, […], page 146

Physick is either curative or preventive.

1650, Thomas Browne, Pseudodoxia Epidemica: […], 2nd edition, London: […] A[braham] Miller, for Edw[ard] Dod and Nath[aniel] Ekins, […]

Any previous counsel or preventive understanding.

1678, Ralph Cudworth, The True Intellectual System of the Universe

Dogs should be warmly but airily housed; heartily, but not heatingly, fed — old Indian meal, mixed with oatmeal, suppawn, is the best general food, with a small quantity of salt, which is a preventive against worms […]

1856, Henry William Herbert, The Complete Manual for Young Sportsmen

Eaten with sugar yaourt is very palatable and refreshing in warm weather and is said to be a preventive of fever.

1885, Cyprus guide and directory, page 82