Relatively speaking, it may have many branches (6,4)
I believe the answer is:
family tree
This could be a double definition.
'relatively speaking' is the first definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'it may have many branches' is the second definition.
The definition suggests a singular noun which matches the answer.
Can you help me to learn more?
(Other definitions for family tree that I've seen before include "Personal history" , "Genealogical chart" , "Chart of relations" .)