GTVA Colossus ship type debate
Ambiguous evidence in canon
In-game dialog simply calls the Colossus a warship. "Warship" is used as a generic term in FreeSpace to designate all combat-capable ships of cruiser size and above. In the second stage of The Great Hunt's mission briefing, even a Rakshasa is simply called a "warship."
A small block of text in the Colossus cutscene refers to the Colossus as a "TVA battle ship of massive proportions". However, there are a number of discrepancies between confirmed canon information and the FreeSpace 2 cutscenes. For example, the Colossus cutscene itself is inconsistent with the size and armament of the in-game Colossus. Additionally, large blocks of text in cutscenes were often filled with nonsensical placeholder text. An out-of-universe explanation for this is that the cutscenes were made in a separated studio, and were not overseen by Volition. More information on cutscene inconsistencies can be found here.
Regardless, the full designation was probably not entirely serious.
In a forum thread at Hard Light Productions, fans suggested the juggernaut designation. According to a poll, 59 members (62.8%) referred to the Colossus as a juggernaut, with superdestroyer being in a distant second place with 17 votes (18.1%). The community appeared to agree that the juggernaut designation would be the most fitting for the Colossus, being the Terran equivalent of the Shivan Juggernaut Sathanas. The Sathanas class is explicitly referred to as a juggernaut, so logic would dictate that a warship that is on par with it would also be classified as a juggernaut. However, this is never explicitly stated in-game.
The term "juggernaut" originates from Sanskrit Jagannātha, one of the names of Krishna. The term has passed into regular English usage to mean an unstoppable, destructive force.
The term "superdestroyer" is used to refer to the SD Lucifer in order to distinguish it from other destroyers in FreeSpace 1. The Colossus may be distinguished from other destroyers in the same fashion. However, designating the Colossus as a superdestroyer would imply that it is on par with the SD Lucifer. This comparison is undermined, however, by the vast differences in size and armament between the two ships. The GTD Hades would likely be a better example of a Terran-designed superdestroyer, as it is explicitly stated to be an attempt at recreating the Lucifer, and has nearly identical stats in its sole canonical appearance, Silent Threat.
Super capital ship
The Colossus is given the "supercap" flag in its ships.tbl entry. This is the same flag that is used for the SJ Sathanas, which is explicitly referred to as a juggernaut in-game. Additionally, the Colossus model file is named "TerranSuper.pof". Nevertheless, the Colossus is never explicitly called a "super capital ship" in any text in FreeSpace 2.
In FRED, the Colossus' short name is "TSoup". The Colossus' texture files also make reference to "TSoup", being named TSoupTile##. The more obvious contraction "TSup" is actually already used to refer to support ships. For comparison, the Sathanas' short name is defined as "SDev", perhaps meaning "Shivan Devil". These are defined in the ships.tbl.