The ILiquidDefinition defines the liquid an ILiquidStack consists of. Unlike the ILiquidStack, this interface allows you to change fluid properties.

It might be required for you to import the package if you encounter any issues (like casting an Array), so better be safe than sorry and add the import.
import crafttweaker.liquid.ILiquidDefinition;

So, what can we do with it?

Multiplying a ILiquidDefinition results in a new ILiquidStack with the specified amount in millibuckets

ZenScript
 Copy
val def = <liquid:lava>.definition;

//essentially the same
val bucketOfLava = def * 1000;
val bucketOfLava1 = <liquid:lava> * 1000;

As an ILiquidDefinition represents a liquid, you can get, but also set it's properties. Check the table below for further information.

Like in the table above, you set the Zengetter/Setter at the end of the ILiquidDefinition. Some ZenGetters have no according ZenSetter, you will need to rely on other means to alter these properties.

Be careful with Zensetters though, they only alter the fluid registry and have no effect on fluids in the world. You will probably only need the temperature setter when messing with Tinkers' Construct Smeltery fuels.

ZenScript
 Copy
val definition = <liquid:lava>.definition;

//Zengetter: luminosity
val lavaL = definition.luminosity;

//Zensetter: luminosity
definition.luminosity = 0;

Zengetter	Zensetter	What is this?	Return/Set Type
Zengetter nome	Zensetter ​	What is this? This returns the unlocalized liquid name	Return/Set Type string
Zengetter displayName	Zensetter ​	What is this? This returns the localized liquid name	Return/Set Type string
Zengetter luminosity	Zensetter luminosity	What is this? This returns/sets the luminosity of the referred liquid	Return/Set Type int
Zengetter density	Zensetter density	What is this? This returns/sets the density of the referred liquid	Return/Set Type int
Zengetter temperature	Zensetter temperature	What is this? This returns/sets the temperature of the referred liquid	Return/Set Type int
Zengetter viscosity	Zensetter viscosity	What is this? This returns/sets the viscosity of the referred liquid	Return/Set Type int
Zengetter gaseous	Zensetter gaseous	What is this? This returns/sets whether the referred liquid is gaseous	Return/Set Type boolean