1cour·te·sy 
/ˈkɚtəsi/ noun
plural cour·te·sies /ˈkɚtəsi/ noun 1 [noncount] : polite behavior that shows respect for other people
▪ They treated us with courtesy and kindness. ▪ He didn't even have the common courtesy [=he was not even as polite as people can usually be expected to be] to say goodbye when he left. 2 [count] a : something that you do because it is polite, kind, etc.
▪ She did it as a courtesy, not because she had to.
b : something that you say to be polite especially when you meet someone
▪ Everyone knows each other here, so we won't bother with the usual courtesies. ▪ They shook hands and exchanged courtesies before beginning their discussion.
▪ They treated us with courtesy and kindness. ▪ He didn't even have the common courtesy [=he was not even as polite as people can usually be expected to be] to say goodbye when he left.
▪ She did it as a courtesy, not because she had to.
b : something that you say to be polite especially when you meet someone
▪ Everyone knows each other here, so we won't bother with the usual courtesies. ▪ They shook hands and exchanged courtesies before beginning their discussion.
courtesy of
◊If you say that something has been provided through the courtesy of or (by) courtesy of a person, organization, business, etc., you are politely saying that they paid for it, gave it, or let it be used.
▪ The flowers were provided through the courtesy of a local florist. ▪ This program is brought to you courtesy of our sponsors. [=it has been paid for by our sponsors] The word courtesy is sometimes used informally by itself in this way. ▪ Photo courtesy Helen Jones. [=Helen Jones is allowing the photograph to be used] The phrase courtesy of is sometimes also used informally to indicate the cause of something. ▪ I have a bad cold now, courtesy of my brother. [=I have a bad cold that I caught from my brother]
▪ The flowers were provided through the courtesy of a local florist. ▪ This program is brought to you courtesy of our sponsors. [=it has been paid for by our sponsors] The word courtesy is sometimes used informally by itself in this way. ▪ Photo courtesy Helen Jones. [=Helen Jones is allowing the photograph to be used] The phrase courtesy of is sometimes also used informally to indicate the cause of something. ▪ I have a bad cold now, courtesy of my brother. [=I have a bad cold that I caught from my brother]
