undercover

adj

1. Performed or happening in secret.
2. Employed or engaged in spying or secret investigation.

noun

1. A person who works undercover.

   “Then there's the heterosexual, open-mined ^([sic]) entourage who loves us dearly and are our best friends. They laugh at our humor and understand our sorrow. For they are rare and unique in prison. But the vipers always ruin things. They refer to our straight friends as "Closet-Cases," "Undercovers," and "Flip-Floppers."”

verb

1. To provide too little coverage.

   “The estimates of bias reported here depend on the assumption that 6- to 14-year-olds were undercovered at the same rate as children 0 to 14 years old and that 16- to 17-year-olds were undercovered at the same rate as 16- to 19-year-olds.”

   “To oversimplify, if black males age 20 to 29 are undercovered by 50 percent, then the first stage sampling weights for black males age 20 to 29 are doubled to properly sum to known population totals.”