Real Dictionary

upgrade
If equipment or services are upgraded, they are improved or made more efficient.

upgrade in American English
an upward slope, esp. in a road
to enhance or improve one's condition, status, capabilities, etc.
to promote to a more skilled job at higher pay
uphill; upward
adjective: uphill; of, pertaining to, on, or along an upgrade
adverb: up a slope
intransitive verb: to improve the quality, value, effectiveness, or performance of something
noun: an incline going up in the direction of movement
transitive verb: to promote to a higher grade or rank

upgrade in British English
noun: an improved or updated version of something
verb: to improve or update (something, such as an electronic device)

upgrade in Hospitality
If you upgrade or are upgraded, you change your hotel room to one that is more expensive.