Definition of wadiy in Arabic
Wadiy in Arabic refers to the thick white fluid which is emitted after passing urine.
The difference between maniy, madhiy and wadiy is in their characteristics.
Shaykh Ibn `Uthaymin (may Allah have mercy on him) said, explaining the difference between maniy, madhiy and wadiy:
The difference between maniy and madhiy is that maniy is thick and has a smell; it gushes out in spurts when desire is intense. As for madhiy, it is a thin liquid that does not smell like maniy; it does not gush out, and it is not emitted when desire is intense; rather it is emitted after desire cools down, and when it cools down, the man becomes aware of it.
As for wadiy, it is a liquid that is emitted after urinating; it is white drops that come when one has finished urinating.
This has to do with the nature of these three things.
The Islamic rulings having to do with maniy, madhiy and wadiy
With regard to the rulings on them, wadiy comes under the same rulings as urine in every regard.
Madhiy differs somewhat from urine in the way in which the individual purifies himself from it, because its impurity (najasah) is milder; therefore it is sufficient to sprinkle water on it, which means making the water reach everywhere it got onto, without the need to wring out the garment or rubs it. Similarly, he must wash his entire penis and testicle, even if it did not get onto them.
As for maniy, it is pure (tahir) and it is not required to wash whatever it got onto, except by way of removing its traces only, and it necessitates ghusl. As for madhiy, wadiy and urine, they all necessitate wudu.
End quote from Majmu` Fatawa Ibn `Uthaymin, 11/169.
For more information, please read the following answers: 2458, 166106, 99507, 47693, 49752, 12223, 81774.
And Allah knows best.