courtesy /kûrtˈə-si or körtˈ/ noun

1. Courteous behaviour
2. An act of civility or respect
3. A curtsy (obsolete)
4. (until 1964) the life interest of the surviving husband in his wife's heritable property (Scots law)

To make a curtsy

courtesy light noun

A small light in a motor vehicle, usu operated by the opening and closing of the doors

courtesy title noun

A title really invalid, but allowed by the usage of society, as for children of peers

(by) courtesy of

1. With the permission of
2. By the favour of

remember your courtesy (obsolete)

Please put on your hat

strain courtesy see under strain¹