The phrase "synonyms incompleteness" is an odd construction.
"Synonyms" is a plural noun that pertains to words with equivalent or similar meanings. For instance, "start" and "begin" are synonyms. It represents a category or collection of related words.
"Incompleteness", on the other hand, is a noun that describes the quality or state of being not whole or lacking some essential parts.
When combined as "synonyms incompleteness", it fails to form a typical, grammatically correct, and semantically clear expression. A more proper way might be "the incompleteness of synonyms", which would convey the idea that there is a lack or deficiency within the body of synonyms. This construction would be more in line with how we usually express the concept of something being incomplete in relation to a particular entity or group, in this case, the set of synonyms. Without the correct preposition or possessive form, the original phrase seems jumbled and difficult to interpret precisely.