Some words used within the classical music profession are interpreted differently by non-specialists. 'Leader' is a good example. We are told that: 'On the visit to China, Simon Rattle led the Berlin Philharmonic.'
No he didn't. Simon Rattle doesn't ever lead; he conducts, or directs, the Berlin Philharmonic Orchestra. The person who leads an orchestra is the section principal of the first-violins, the person whom the Americans call the concertmaster. Leaders don't wield batons.
Outside the classical music profession a similar confusion now surrounds the term 'song'. Look at popular websites. Only a few contemporary contributors use the words 'melody' or 'tune', and those words are never used if the writer is young, or pop-oriented. What were formerly referred to as refrains, airs or arias (how unfashionable those words must sound to young ears fed a diet of pop music), are now described as 'songs'.
In the browser bins of one Yorkshire music retailer I see a collection of tunes for clarinet called Book of Clarinet Songs. Surely, the publication should be called Book of Clarinet Tunes, or Book of Clarinet Melodies? Songs are for singing. Clarinets don't sing, much as we clarinettists wish that they would. Only people, birds, whales - and some cats - sing. On sites such as YouTube, 'song' has taken over completely from its various synonyms. For a while, I took up the cudgels and, irritably, I wrote to correct any YouTube commentator who called a concerto or a sonata a 'song'. That is a waste of time, I assure you.
In the browser bins of classical music shops I see a folio called Ten Great Blues Songs. The contents include Solitude, Lover Man and Cry Me a River. Not one of those three is actually a traditional blues. By the definition of most educated musicians a blues usually has a twelve bar cyclic form, the basic type never wandering far from the three primary triads. The melodies mentioned in the folio are really show tunes, not blues. Yes, these are sad or poignant tunes - but sad is not the same as blues. A similarly irritating publication purports to contain 'blues greats', among which are Hoagy Carmichael's Georgia, George Gershwin's The Man I Love and Angel Eyes, by Matt Dennis. I recognise no connection with the form or spirit of the blues here, either. These are commercially produced pop songs (very good ones), with clever chromatic harmony and AABA form, dating from the mid-twentieth century. In this instance the finger of suspicion over the label 'blues' points to the work of the publisher's marketing department. Probably they are not musicians.
Of course, words change. Think of the American meaning of words like vest, pants, and suspenders. I wonder, are we in the process of similarly losing the original meaning of the musical terms I mention? Just as we seem to have taken to referring to a railway station as a train station - which I confess to disliking, even though it is underlined by the parallel bus station - the wireless has changed into a radio, we no longer admire the cut of a man's jib, and we are slightly unsure of what it means to cut a dash.
The three-syllable word saxophone has all but disappeared, gone the same way as telephone, luncheon, omnibus and applications (as in iPhone applications). Now, almost everyone writes and speaks of the phone, lunch, the bus, apps - and the sax. How do players of the saxhorn feel about sax, I wonder? And notice, please, which fellow musicians don't call it a sax. Serious saxophonists, that's who. They usually give it the full name. For instance, the late Sir John Dankworth nearly always said, and wrote, saxophone, not sax.
Laziness, or maybe a process of simplification (or more likely plain old ignorance), is also responsible for depriving songwriters of their due credit. For example, German composer Kurt Weill's best known work is The Threepenny Opera, which contains his most famous song, Mack the Knife. But frequently one hears (and reads) the credit being given to performers, as in: 'Ella Fitzgerald's song Mack the Knife'. On the internet one can find lyrics to Summertime, 'By Dame Kiri Te Kanawa'. Porgy and Bess (from which it comes) was written by George Gershwin and DuBose Heyward, as you know. Dame Kiri merely sings Summertime, but she frequently receives composer credits from those who don't know any better.
So, what's to be done? I haven't a clue. You tell me.