"Make sure all the field observations are classified by species."
2.AdjectiveSorted into classes or categories.
3.AdjectiveFormally assigned by a government to one of several levels of sensitivity, usually (in English) top secret, secret, confidential, and, in some countries, restricted; thereby making disclosure to unauthorized persons illegal.
"We do not discuss specific interrogation techniques because they are classified information."
4.AdjectiveNot meant to be disclosed by a person or organization.
"I won't say who I'm going to the prom with; that's classified."
5.NounA classified advertisement in a newspaper or magazine.
"He ran a classified for the tools he wanted to sell."