from The Century Dictionary.
- Proof against plots; not to be hurt by a plot or plots.
from the GNU version of the Collaborative International Dictionary of English.
- adjective Secure against harm by plots.
Sorry, no etymologies found.
And if, when subdued, she knows but how to middle the matter between virtue and love, then will she be a wife for me: for already I am convinced that there is not a woman in the world that is love-proof and plot-proof, if she be not the person.