assemble or accumulate something by putting parts or material together

he was an obsessive collector of paintings, drawings, and sculpture, and he built up a huge collection

over the years she has built up a lot of contacts from her travels

make a person or their body stronger

if you want to build yourself up you can go to the gym

physical exercise builds up your muscles

become stronger or more intense; grow or accumulate

I felt tears building up in my eyes

harmful chemicals build up in a fire

so much mistrust has built up over the years