The official FJTM list of dreadnoughts is:
2100 Federation
2101 Star League
2102 Unificatum
2103 Compact
2104 Corporation
(this space left blank intentionally
)
2106 Konkordium
2107 Star System
2108 Affiliation
2109 Concordat
2110 Directorate
2111 Organization
2112 Star Union
2113 Alliance
2114 Confederation
2115 Dominion
2116 Star Empire
2117 Trusteeship
2118 Association
2119 Consortium
2120 Entente
Anything past 2120 is something made up by SFB or someone else, not that there's anything wrong with that.
Oddly enough, ol' Franz seems to have completely missed 2105. ???
These names seem to come from political organizations within the Federation. For example, in Franz' world, the official name for the Vulcan government is "Planetary
Confederation of 40 Eridani."
Star Empire is named after the "Star Empire of Epsilon Indii," and
Konkordium is named after the "Alpha Centauri Concordium of Planets" (Alpha Centauri seems to use some sort of Greek-inspired lettering system where the letter "K" is used in place of "C"). The only other two governments he mentions specifically are the "United Nations of Earth" and the "United Planets of 61 Cygni;" perhaps one of these was meant to become the namesake of NCC-2105?