An upward grade or slope.

An improved component or replacement item, usually applied to technology

“With my phone company, I get a free upgrade every twelve months if I keep topping up 10 pounds a month.”

An improvement

“The remarried couples among my friends often joked that their divorce and remarriage amounted to an upgrade.”

To improve, usually applied to technology, generally by complete replacement of one or more components

“When you upgrade your standard of living, you become addicted to that standard of living.”

To replace with something better.

“I had to upgrade my anti-virus software to protect my computer from the newer threats.”

To improve the equipment or furnishings of or services rendered to

“They upgraded him to the latest model.”

Up a slope or grade.