Explorer

In starship classification, an explorer is a multi-role starship, equipped for a wide variety of tactical, scientific and diplomatic capabilities. Vessels of this type are similar to heavy cruisers in that they carry considerable defenses, and are intended to perform long-duration missions, lasting numerous Earth years.

The Galaxy class is an example of this type of ship. (TNG: "Yesterday's Enterprise")

The early NASA ship Charybdis was also classified as an explorer, although ships of that era had limited capabilites in comparison the the Starfleet usage of this term. (TNG: "The Royale")
 * The "explorer" type is derived from the original designs, graphics and technical drawings of the Enterprise-D by Andrew Probert, Rick Sternbach and Michael Okuda. More information about the explorer designation exists in the Star Trek: The Next Generation Technical Manual. This designation was mentioned in the script of TNG: "Yesterday's Enterprise", noting that the alternate timeline Enterprise''-D differed from the familiar explorer-type ship. Some concider the term "Explorer" to be short hand for "Large Exploratory Cruiser."