An elderly gentleman I know often refers to a quite a few managers in the insurance industry as “my students”, but he says “talebem” not “öğrencim” when doing this.
He also refers to the professional organization he helped found as a “cemiyet,” not the “dernek” of its modern title. In the street where I live is a school whose official name includes the old word “mektep” — although the signs outside warn drivers that this is an “okul.”
Turkish children have been “öğrenci” not “talebe” and going to an “okul” not a “mektep” for over 80 years. But still, when addressing their teacher they are as likely to say “hocam” as “öğretmenim.” Some old words have totally fallen out of currency, being replaced by the new ones. Others have kept their usage. Why?
All languages change and develop. You only have to pick up a piece of English prose written a century or two ago to find a number of changes in meaning. My mother’s generation still often refers to feeling “gay” as being happy and light-hearted. Other words totally drop out: My father used to refer to “blacking” instead of “shoe-polish” and a “pinafore” for an “apron.” We all knew what he meant, but go back a few centuries and a few words can be totally unrecognizable.
But the changes that Turkish underwent in the 20th century were not the result of natural evolution — as words gradually took on new shades of meaning, and people dropped some in favor of others as fashions changed. Turkish was subject to a deliberate re-engineering.