'Stealth' means that you are doing something without somebody or some animal knowing or noticing what you are doing. "Lions catch their prey using stealth." "The stealth bomber cannot be detected by radar." "An assassin usually uses stealth to accomplish their purpose, going unnoticed or undetected until it is too late."

Stealth is to move or operate in a quiet or sneaky fashion, so as to escape the attention of someone. "The teenager slunk stealthily back into his house, so that his parents would not notice he had been out all night partying." "The company wanted to develop their new product with great stealth, so that their competitor would not learn about their ideas." "The international spy was a master of stealth, able to sneak into secure buildings without arousing any suspicion."