How to discretize a numerival value with predefined ranges in Weka?
Discretising or binning, very common. There is a filter for that in Weka. You'll find it under weka.filters.unsupervised.attribute.Discretise. It is in the GUI too. 

You can find the documentation under: https://weka.sourceforge.io/doc.dev/weka/filters/unsupervised/attribute/Discretize.html