Where does “cyanurin” come from?

cyanurin (English) comes from English cyanuria, from English -uria, from Latin -ūria, from Ancient Greek -ουρία, from Ancient Greek οὖρον, from Proto-Indo-European h₂wers- — to rain, drip; to rain, sprinkle.

cyanurin (English): The pigment that gives the urine a bluish tinge...

Definitions

The pigment that gives the urine a bluish tinge...

Ancestry of “cyanurin”, step by step

cyanurin traces back through two separate lines of ancestry.

via English cyanuria

Step	Language	Word	Meaning
1	English	cyanuria	The passing of bluish-coloured urine
2	English	-uria	Relating to urine
3	Latin	-ūria	—
4	Ancient Greek	-ουρία	—
5	Ancient Greek	οὖρον	urine; range, space; accusative singular of οὖρος
6	Proto-Indo-European	h₂wers-	to rain, drip; to rain, sprinkle

via English in

Step	Language	Word	Meaning
1	English	in	Used to indicate location, inclusion, or position...
2	Middle English	in	Any kind of accomodation; particularly; A home or...
3	Old English	in	in; Alternative form of inn
4	Proto-West Germanic	*in	—

Every word from Proto-Indo-European h₂wers- →Every word from Ancient Greek οὖρον →Every word from English -uria →