The next to highest level of official classification for documents

• Designed to elude detection
• Indulging only covertly
• Not openly made known
• Kept private or not revealed
• Conducted with or marked by hidden aims or methods
• Having an import not apparent to the senses nor obvious to the intelligence
• Not expressed
• Hidden from general view or use

WordNet Word definitions in WordNet
n. any of various organs that synthesize substances needed by the body and release it through ducts or directly into the bloodstream [syn: gland , secretory organ , secretor ]