The word "inhabitancies" is spelled with the letter "a" after "t" because it is derived from the root word "inhabitant". The "-ancy" suffix is added to signify the state or quality of being an inhabitant. In IPA phonetic transcription, it is pronounced as /ɪnˈhæbɪtənsiz/. While this word is not commonly used in everyday language and may be substituted with simpler terms such as "residences" or "dwellings", it can still be useful in certain contexts pertaining to demographics or population studies.
The word "inhabitancies" does not have an established etymology as it is not found in most dictionaries. It appears to be a derivative of the noun "inhabitancy", which refers to the act of inhabiting a place or the state of being inhabited. However, it is important to note that "inhabitancies" is not a commonly used word and its origins might be limited to specific contexts or dialects.