sightproof

Adjective

1. invisible; not able to be seen
   • As it was, whenever the yellowbirds came back, their enemies were hidden in their own sight-proof bush. - 1871, James Russell Lowell, “My Garden Acquaintance”, in My Study Windows, Boston, Mass.; New York, N.Y.: James...
   • This louver may also be used where a sightproof louver is desired. - 1959, Carol J. Dyson, AIA, Louvers in extruded aluminum, Construction Specialties, Inc., page 6:
   • There is no more perfect place for a mugger to catch you than in an almost soundproof, sightproof apartment entranceway as you are fumbling with your keys or reaching for your mail. - 1975, Randall Bassett, “three...