Here's why:
* Usage notes often provide specific information about how a word is used in different contexts, including specific fields, professions, or subcultures.
* Labels (such as "technical," "slang," "informal," or "archaic") indicate how a word is typically used and can hint at its association with certain professions or activities.
For example, a dictionary entry for the word "gauge" might include usage notes explaining how it is used differently in the context of engineering, carpentry, or mechanics.