Undercommon
Undercommon is a strange language, having seemingly appeared out of nowhere. For unknown reasons, it is spoken by those creatures that roam the depths of the world. Even completely unrelated species on different ends of the world still speak a mutually-intelligible version of the language. This is either a result of, or the cause of, it being a terribly simple language---not useful for expressing meaning beyond basic concepts, but the fact that it is so widely known still makes it useful.
Geographical Distribution
Undercommon is commonly spoken throughout the entirity of the Underdark. This is thought to be due to the frequent quakestorms intermixing various sections, leading to a surprisingly homogenous population.
Phonology
Like the syntax and vocabulary, the sounds used in Undercommon are extremely simple, allowing nearly all creatures capable of the mearest resemblance of speech to speak it, no lips or tongue required. This is achieved through a unique general categorization of phonemes, or, as it is more commonly known, the "close enough" approach. As such, two speakers may sound like they are speaking in completely different languages.
To facilitate communication, a common greeting is given at the start of a conversation. This allows both participants to know which sounds to look out for: "BANAHI".
The following sounds are used in Undercommon, indicated by the most common manner of transcribing:
Consonants:
N - Closed mouth consonant (m, n, ŋ, and similar sounds)
B - Closing/opening mouth consonant (b, p, d, t, and similar sounds)
H - Breath consonant (h, g, k, r, ʔ, and similar sounds)
Vowels:
A - Air-out vowel (lower-pitched, louder)
I - Air-in vowel (higher-pitched, softer)
Because the type of phoneme is also closely related to the state of the mouth, even mute or deaf "speakers" are known to exist. Speakers without vocal cords often have difficulty making a distinction between A and H, so they will generally pronounce H as a glottal stop.
Morphology
Words can generally be constructed from any combination of phonemes, as long as they follow these rules:
No repeating vowels. The same vowel can not be repeated, as this is difficult to distinguish from a glottal stop H. (e.g., AA or II is not allowed, but AI or IA is.)
After air-in, an air-out phoneme must follow. The air-in phoneme is too difficult to repeat without also being allowed to let air out. As such, when an I occurs, then before the next use of I within the same word, must come an A or H.
No repeating N consonant. Same as with vowels, the stop between NN can not be distinguished from a glottal stop H. Additionally, with some pronunciations of N, it would be difficult to tell where one ends and another starts.
Max. 3 consonants or vowels in a row. To aid with pronunciation, no more than 3 phonemes of the same type can be used in a row. (e.g., AIA is allowed, but AIAI isn't.)
Dictionary
BANAHI - Greeting
BIH - Affirmative
AHA - Negative
NH - Uncertain / Interrogative
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