used

That is or has or have been used.

The ground was littered with used syringes left behind by drug abusers.

Economics is a messy discipline: too fluid to be a science, too rigorous to be an art. Perhaps it is fitting that economists’ most-used metric, gross domestic product (GDP), is a tangle too. GDP measures the total value of output in an economic territory. Its apparent simplicity explains why it is scrutinised down to tenths of a percentage point every month.

That has or have previously been owned by someone else.

He bought a used car.

In used to.