Final answer:
The common name for tinea unguium is onychomycosis, a fungal infection that affects the nails, making them yellow and brittle.
Step-by-step explanation:
The common name for tinea unguium is onychomycosis. This fungal infection affects the nails and is characterized by symptoms such as the nail becoming yellow, brittle, and prone to breaking. Tinea unguium is caused by a group of fungi known as dermatophytes, which require the protein keratin, found in skin, hair, and nails, to grow. Other types of tinea include tinea corporis (ringworm), tinea cruris (jock itch), and tinea pedis (athlete's foot), each referring to an infection in a specific body location.