General opposites:
* Ignorance: This suggests a lack of knowledge or understanding, which is the opposite of having a wide vocabulary.
* Limited knowledge: This implies a restricted understanding, the opposite of having a wide range of words.
* Unarticulateness: This refers to the inability to express oneself clearly and effectively, which is often associated with a limited vocabulary.
Specific opposites:
* Silence: This is the complete absence of words, the opposite of using vocabulary.
* Inarticulateness: This suggests difficulty expressing oneself clearly and effectively, which is often associated with a limited vocabulary.
* Monotony: This refers to a lack of variety in language, the opposite of a rich vocabulary.
Ultimately, the best antonym for "vocabulary" depends on the specific context and what you are trying to express.