Polyuria is a condition usually defined as excessive or abnormally large production or passage of urine
Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...

 (at least 2.5 or 3 L over 24 hours in adults). Frequent urination
Frequent urination
Frequent urination, or urinary frequency, is the need to urinate more often than usual. It is often, though not necessarily, associated with urinary incontinence and polyuria.A frequent need to urinate at night is called nocturia...

 is sometimes included by definition, but is nonetheless usually an accompanying symptom. Increased production and passage of urine may also be termed diuresis.

Polyuria often appears in conjunction with polydipsia
Polydipsia is a medical symptom in which the patient displays excessive thirst. The word derives from the Greek πολυδιψία, which is derived from πολύς + δίψα...

 (increased thirst), though it is possible to have one without the other, and the latter may be a cause or an effect.