What is the definition or description of: weak urine stream?

Slow flow: Voiding flow rates are a function of the strenght of the bladder muscle and the caliber of the out flow tract including the bladder neck, the prostatic urethra and the penile urethra. Weak stream most commonly occurs with prostatic growth age related narrowing the passage.

See below: The urinary stream becomes weak as in prostate enlargement in men or other causes of obstruction. Usually occurs in late 40's.