"Nelavan" is a unique word with a spelling that is not immediately obvious. However, when broken down phonetically using the International Phonetic Alphabet (IPA), the spelling becomes clear. The first syllable is pronounced /nɛl/, with a short e sound, followed by the second syllable which is pronounced /əvən/. Together, the word is pronounced /nɛləvən/. Although the spelling may not be familiar, the IPA transcription allows for accurate pronunciation of this word.
Sleeping-sickness.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.