Yellow nasal discharge is not a symptom of a cold. A cold, also known as an upper respiratory tract infection, typically presents with clear nasal discharge, indicating a viral infection. The appearance of yellow nasal discharge could suggest two possibilities: it could either be a symptom of sinusitis or it could indicate a secondary bacterial infection following a cold, especially in the later stages of a cold, manifesting symptoms similar to sinusitis. Therefore, yellow or yellow-purulent nasal discharge is definitively not a cold; it might be a symptom of sinusitis occurring late in the course of a cold or as the cold is resolving. In conclusion, yellow nasal discharge is not indicative of a cold.