(broaderTerm TERM1 TERM2) means that TERM2 is broader than TERM1, in an extremely general sense of "broader". For example, TERM2 is, in the relevant sense, broader than TERM1 if any of the following hold:

TERM2 is a collection that subsumes TERM1;
TERM2 is a collection that has TERM1 as an instance;
TERM2 is a collection, instances of which have instances of the collection TERM1 as parts;
TERM2 has TERM1 as a part;

This list of reasons for why (broaderTerm TERM1 TERM2) could hold is not exhaustive, but it should give a good indication of how general the broaderTerm relation actually is.