An isolation suit was a type of stealth clothing used by the FederationStarfleet in the 24th century. The suit was equipped with technology that made the person wearing it practically invisible. It was possible to see through the invisibility when a person wearing the suit was viewed through a specialized screen. The suits were linked to the "duck blind" monitoring station, in that they lost the invisibility effect when the duck blind lost its holographic shell.
In the script of Star Trek: Insurrection, the term cloaked is used of the people using the suits and the term decloaking is used when isolation suits are turned off, but it is also clearly indicated that a force field is responsible for the invisibility. 
The Star Trek Fact Files state that isolation suits use holographic technology rather than a cloaking device to achieve the invisibility. In the novel Lesser Evil, the Trill Hiziki Gard used an isolation suit to evade capture after he assassinated the Bajoran First Minister, Shakaar Edon, on Deep Space 9.