Pre-ejaculatory fluid is a thick and clear fluid released by accessory glands in the penis during arousal. Ejaculated sperm travels must travel through the urethra, the same route that acidic urine passes through. The pre-ejaculatory fluid protects sperm from the acidity of the male urethra and female vagina while lubricating the male urethra.

Pre-ejaculatory fluid can also be referred to as pre-seminal fluid, pre-ejaculate or as pre-cum (the slang term.)