Ancient Tongue
The Ancient Tongue is a preimperial language from which are derived many words and phrases still in use in the Second Konabian Empire. In particular, but not exclusively, many technical terms have their origin in the Ancient Tongue, apparently including those of chemical compounds and biological taxonomic names.
Grammar
The fact that the Ancient Tongue seems to survive only in various (mostly bound) morphemes and fossilized phrases makes it very difficult for linguists to reconstruct anything about it with certainty. Nevertheless, from the scattered examples that exist there are a few things they have been able to deduce. Nouns in the Ancient Tongue seems to have had three different genders, with which adjectives had to be in agreement. Nouns also had at least two different cases, a nominative and a genitive; while there is evidence of other cases besides these two, there are not enough attested words in these cases for linguists to be able to learn for sure whether they represent accusative, dative, ergative, or some other case. As for number, the Ancient Tongue certainly distinguished between singular and plural; some linguists believe there was also a dual number, but the evidence for this is scanty. Nouns seem to have varied widely in their declensions; linguists have tentatively identified at least eight paradigms, along with a number of nouns that may be irregular or may be the only surviving (or only identified) members of other declensions.
While a number of verbs have been distinguished, little is known about their conjugation. The only forms of verbs that have been established with any level of confidence are their infinitives and their past participles, and even here there is disagreement, with some linguists insisting that the parts usually designated the infinitives are really present tense forms or present participles. Based on the few fossilized phrases that are available, verbs in the Ancient Tongue are thought to have different forms corresponding to the person and number of their subjects, but the exact paradigms remain unclear.
Pronouns and prepositions from the Ancient Tongue survive only in a few sparse fossilized phrases, and very little is understood about their forms and grammar. It is primarily the nouns, adjectives, and verbs of the Ancient Tongue that are known.
Usage
Many preimperial words deriving from the Ancient Tongue remain in common use, and many linguists even believe the Ancient Tongue to be ancestral to some of the languages spoken in the Empire. This does not, however, represent the extent of its current use. As much out of tradition as anything else, new technical terms and other words continue to be coined using the Ancient Tongue. Because so little is known about the Ancient Tongue, this is done mostly by analogy with existing words, and by assumptions about what those parts mean; scholars are not unaware of the shakiness of those assumptions, but realize that for the moment it's the best they can do.
Likewise, the Ancient Tongue continues to be used to some extent for the scientific names of newly discovered organisms, as well as for the names of higher taxa. Here, however, the great number of names needed makes it impractical to rely solely on what few vestiges of the Ancient Tongue can be picked out of known words. Rather, a few established prefixes and roots are sometimes strung together, but biologists rely heavily on other sources for scientific names, including proper nouns and words of other languages.
Theories
Despite the paucity of firm information about the Ancient Tongue, some linguists have developed various theories about it. Perhaps the most prominent and most interesting theory is that the Ancient Tongue isn't actually a single language at all. Though not all agree, many linguists point to various factors—such as the fact that most important words have at least one synonym, and certain patterns of grammar and of which words appear jointly together—as evidence that what is now called the "Ancient Tongue" is actually at least two different (though possibly related) languages which have become conflated.
There also seems to be evidence that the culture(s) behind the Ancient Tongue may be the same one(s) also behind some of the oldest known preimperial legends. The names of many of the still-remembered grandeval mythological figures, such as Medusa and Pan, are often found in conjunction with snippets in the Ancient Tongue. While some historians have attempted to divine from elements of these myths more about the preimperial people who spoke the Ancient Tongue, the task is rendered all but insperable both by the difficulty of teasing out which myths actually belong to that culture (since it's by no means clear that all known preimperial myths have the same origins), and by the irreconstructible ways that the myths have no doubt evolved over time.