duty >> /ˈd(j)udi/
Definition: [noun] A moral or legal obligation; a responsibility.
Example: it's my duty to uphold the law
Definition: [noun] A task or action that someone is required to perform.
Example: the queen's official duties
Definition: [noun] A payment levied on the import, export, manufacture, or sale of goods.
Example: a 6 percent duty on imports
Definition: [noun] The measure of an engine's effectiveness in units of work done per unit of fuel.