insuppressible

in- +‎ suppressible

insuppressible (comparative more insuppressible, superlative most insuppressible)

1. That cannot be suppressed.
   • 1903, William Godwin, Caleb Williams‎:

     It seemed as if the sense of public resentment had long been gathering strength unperceived, and now burst forth into insuppressible violence.

   • 1921, Louis Joseph Vance, Red Masquerade‎:

     In its stead Victor favoured Karslake with a slow smile of understanding that broadened into an insuppressible grin of successful malice, a grimace of crude exultation through which peered out the impish savage mutinously imprisoned within a flimsy husk of modern manner.