upgrade /ˈʌpgreɪd/ noun [C]
› an improvement in something: All our office furniture needs a major upgrade. → Compare downgrade
› IT a piece of software or equipment that improves how well a computer or machine works: The basic software is free but you pay for any upgrades.an upgrade to sth The upgrade to version 5.0 costs $395.
› better travel arrangements than you originally paid for: an upgrade to sth We got a free upgrade to first class!