A triangle with all sides equal is called an equilateral triangle, and a triangle with no sides equal is called a scalene triangle. An equilateral triangle is therefore a special case of an isosceles triangle having not just two, but all three sides and angles equal.
In medicine, specifically urology, dysuria refers to painful urination. Difficult urination is also sometimes, but rarely, described as dysuria. It is one of a constellation of irritative bladder symptoms (also sometimes referred to as lower urinary tract symptoms), which includes nocturia and urinary frequency.
Dysuria is an extremely common symptom in women, but it can occur in men and can occur at any age. Dysuria results from irritation of the bladder trigone or urethra. Inflammation or stricture of the urethra causes difficulty in starting urination and burning on urination. Irritation of the trigone causes bladder contraction, leading to frequent and painful urination. Dysuria most frequently results from an infection in the lower urinary tract, but it could also be caused by an upper UTI. Impaired renal concentrating ability is the main reason for frequent urination in upper UTIs.