Which term describes any substance expectorated through the mouth?

The term "sputum" is used to describe any substance that is expectorated through the mouth, specifically relating to the mixture of saliva and mucus that is coughed up from the respiratory tract. Sputum is often analyzed in medical settings to help diagnose respiratory conditions such as infections or chronic illnesses, as it can contain pathogens, inflammatory cells, and other substances which are diagnostic indicators.

While the other terms relate to respiratory secretions, they have more specific meanings. For instance, "sputa" refers to the plural form of sputum but is less commonly used in practice. "Phlegm" is more specifically the thick mucus produced in the respiratory passages, often associated with illness but doesn't cover the entire spectrum of substances that may be expectorated, which could include additional fluids or particles. "Rhinorrhea" refers to an excessive amount of mucus produced in the nasal cavity, which is not related to expectoration through the mouth but rather to nasal discharge. Thus, "sputum" is the most accurate and widely accepted term for substances expectorated through the mouth.