What is the definition or description of: urethral stricture?

Urethra: Urethral stricture is a narrowing of the urethra most commonly in males due to stds, precious surgery or instrumentation.

It is...: It is the narrowing ring(s) or segment of the urethra from bladder neck to its very end (urethral meatus) so to interfere urine flow and generate high back-up pressure above the narrowing although usually denoting its occurrence in anterior urethra (from sphincter to meatus). It may be caused by various reasons - infection, trauma/injury, or inborn, etc.