consolidate
verb
unite into one
“The companies consolidated”
make firm or secure; strengthen
“consolidate one's gains”
“consolidate one's hold on first place”
bring together into a single whole or system
“The town and county schools are being consolidated”
form into a solid mass or whole
“The mud had consolidated overnight”
make or form into a solid or hardened mass
“consolidate fibers into boards”
Source: WordNet 3.1, Princeton University