So often we work in small groups of a covert nature, but here was the chance to be out in the open in large numbers.

Dr. Fletcher said he was particularly concerned by the covert nature of the study.

Although hazardous, the boat ride was relatively short and its covert nature was easier to conceal than a comparable land journey.

The Ministry of Defence has not released further details due to the covert nature of the mission.

One reason is the covert nature of the dealings; it is illegal, so gaining hard evidence is not an easy feat.

It was easier with the Maquis because she'd rarely had to stare down her enemy; the covert, anonymous nature of their war assured that.

If she retains her covert nature, we keep the element of surprise.

It is difficult to determine how frequently ghostwriting occurs due to its covert nature.

The covert nature of the project was far more important than the actual number of warheads, those in authority had decided.

The official, who is closely involved in the case, spoke on condition of anonymity because of the work's covert nature.