Hapax Legomenon
In corpus linguistics, a hapax legomenon is a word that occurs only once within a body of work: either in the written record of an entire language, in the works of an author, or in a single text. Hapax legomenon is a transliteration of Greek ἅπαξ λεγόμενον, meaning “being said once”.
In the ancient Hebrew codices contain 3000 words that occur only once. This is nearly a third of the total lexicon. These words are impossible to cross validate contextually, and therefore their meanings can only be guessed at based on the context of a single instance. In other words, they are not well attested
An additional 1500 words occur only twice, and about another 1000 occur three times.
Over 7000 of the words occur less than ten times.
In contrast, there are only 430 well attested words that occur more than 100 times within the corpus. The meanings of these words are easy to determine using contextual comparison. To put that into perspective, this means that out of the 9600 words in the corpus, less than 4.5% are readily translatable.