A core name was a shortened name used by Chiss. Members of the Chiss species used their core names rather than their full names for at least two reasons. Among Chiss, core names were used in all but the most formal settings. Chiss also gave their core names to members of other species, as non-Chiss had difficulties pronouncing full Chiss names.
Core names were abbreviated forms of the full names of Chiss. Most Chiss names were multi-syllabic and consisted of three distinct parts, as in "Mitth'raw'nuruodo". The first part, before the first apostrophe, represented the Chiss family to which the name's bearer belonged. The second part, between the two apostrophes, was the person's given name. The third part of the name, after the final apostrophe, represented other social factors.
Chiss used their core names when speaking to individuals of other species, who were often unable to pronounce the full Chiss name. When meeting Jedi General Anakin Skywalker on Batuu, Mitth'raw'nuruodo of the Chiss Expansionary Defense Fleet suggested using his core name of Thrawn. Core names were also used among Chiss in all but the most formal settings, and were even used in some formal settings after initial introductions with one's full name.
Core names were composed of the final part of one's family name, all of one's given name, and the beginning of one's social factor suffix, without interleaved apostrophes. Because a Chiss' family name formed part of their core name, individuals' core names would change upon their rematching into a new family. The sky-walker navigators and flag officers of the Chiss Defense Force did not belong to any one Chiss family, but rather to the "family" of the Chiss Ascendancy. In those cases, the names were two-part and were not abbreviated to core names.
When Chiss joined a new family, their full names and core names changed as well. This could occur during rematching, military promotion, or adoption.
The Chiss who would one day become feared as the Imperial Grand Admiral Thrawn was born as Vurawn, with his new core name only coming once he was adopted into the Mitt family.
An example of a name that changed over time is Mitth'raw'nuruodo, born as Kivu'raw'nuru "Vurawn". Vurawn was made a merit adoptive of the Mitth family, thus changing his name to "Mitth'raw'nuru" and his core name to "Thrawn". Similarly, the sky-walker Al'iastov was adopted into the Mitth family, thus becoming Mitth'ali'astov and gaining the core name "Thalias".
Irizi'rik'ardok "Zirika" married a man from the Cohbo family, thus making her name Cohbo'rik'ardok with the core name of Borika. The family name was switched from the previous family to the family in which the individual was marrying into.
Another Chiss whose name changed over time was Admiral Ar'alani, born Irizi'ar'alani "Ziara". Ziara was a Blood member of the Irizi family. Upon her promotion to commodore, Supreme Admiral Ja'fosk declared that Senior Captain Irizi'ar'alani was no more, and in her place arose Admiral Ar'alani. Ar'alani reflected that the same had once happened to Ja'fosk, and Patriarch Mitth'oor'akiord told Caregiver Thalias of a time when Ba'kif was known as "Labaki". Being a part of the Irizi family, Ziara was loyal to them and the Chiss Ascendancy. However, when getting promoted to a rank of commodore or higher (known as a flag officer), Chiss were stripped of their family names and ties to ensure their loyalties to only the Chiss Ascendancy.
Becoming a sky-walker entailed leaving your original family to work for the Chiss Ascendancy at a very young age. This also came with losing the name of the individual's original family. Kivu'rik'ardok "Vurika" was once a member of the Kivu family, but upon being taken away to become a sky-walker at five years old, she was assigned the name Rik'ardok; losing the family name. Sky-walkers served the Chiss Ascendancy only, and thus they were recognized with no family ties. Upon retiring as a sky-walker, they would receive a new family to get adopted into--typically a Ruling Family because of the honor it would bestow upon them. Rik'ardok got adopted into the Irizi family and received the name of Irizi'rik'ardok with the core name of Zirika.
Honoring ceremonies were ceremonies to honor Chiss individuals for their contributions to the family or the Chiss Ascendancy. One such honoring ceremony, the Stybla honoring ceremony, celebrated an individual who has guarded or protected the Stybla from any threat. The ceremony brought forth the suffix "odo" to the end of the Chiss name. Mitth'raw'nuruodo is one such individual who received the honor by the Stybla even though he was not related to the Stybla family; the core name would stay the same: Thrawn.
Some examples of core name derivation from an individual's full name follow.
Notably, the human Eli Vanto, a rare human alien in the service of the Chiss Ascendancy, did not belong to any Chiss family. Instead, his given name "Eli" was treated as the equivalent of a Chiss family within his name, and he was thus given the core name "Ivant". At first, Vanto disliked the core name he had been assigned by his Chiss colleagues, preferring they address him as "Eli" as other humans would. However, he eventually came to see his core name as a sign that he had truly been accepted as a member of the Chiss Ascendancy.
Upon promotion to flag rank (commodore and higher), Chiss officers were stripped of their family ties and name, being officially recognized as "The Ascendancy is your family". Similarly, Force-sensitive Chiss children were taken from their families of birth to serve as "sky-walkers", and were likewise treated as having no specific family. Those individuals' names were two-part instead of three and were not abbreviated to a core name.
Core names first appeared in the revivified canon in the 2016 television movie Star Wars Rebels: Steps Into Shadow. They were first identified as core names in the 2018 novel Thrawn: Alliances by Timothy Zahn.
Core names first appeared in the Star Wars Legends continuity in the 1991 novel Heir to the Empire, also by Timothy Zahn. They were first identified as core names within Star Wars Legends in Zahn's August 1995 short story Mist Encounter, which portrayed Thrawn's first contact with the Galactic Empire.
Chiss name changes first appeared in Thrawn Ascendancy: Chaos Rising by Timothy Zahn when Kivu'raw'nuru got adopted into the Mitth family as Mitth'raw'nuru.