Ulcus

Ulcer, crater; an ulcer always means a loss of tissue; in contrast a tumour is always an increase in tissue

Ulnar deviation

A typical sign of chronic polyarthritis, a deviation of all long fingers from the thumb

Uni

Prefix meaning, one, single, one-sided, alone

Unicondylar

Concerning only one joint head, e.g. in the case of knee prostheses where only one side is replaced, either on the inside or, more rarely, only on the outside

Unilateral

One-sided, only affecting one side of the body

Uveitis

An inflammation of the iris of the eyes