This is the 11575th most frequent German word.
stoff
Material; substance; fabric.
Here, 'Stoff' refers to fabric or material as a tangible textile resource.
Ich habe neuen Stoff im Geschäft gekauft.
I bought new fabric at the store.
In this usage, 'Stoff' metaphorically refers to material for intellectual discussion purposes.
Das Buch bietet interessanten Stoff für Diskussionen.
The book provides interesting material for discussions.
Here, 'Stoff' is used in a scientific context to mean a substance or matter being analyzed.