The word defectivenesses is uncommon and may not have many synonyms readily available. However, some possible synonyms that could convey a similar meaning include flaws, imperfections, deficiencies, weaknesses, degeneracies, or insufficiencies. Each of these words reflects a sense of something being incomplete or lacking in some way. Additionally, words like abnormalities, irregularities, or aberrations could also be considered synonyms for defectivenesses, as they imply a deviation from the norm or standard. Ultimately, the choice of synonym will depend on context and the specific nuance being conveyed, but these words all share the underlying idea of something being less than ideal.