Where I come from in the US, if you say "the senior" without any specific context, you assume at first that they mean someone in there 4th/last year of high school or college (university). The senior citizen would be more common expression. We use "retiree" for someone who has retired from work. We do sometimes use "senior" to refer to an elderly person, but it usually is in a specific context, like: "Seniors get 20% of the early bird special," an example of a "Senior Discount." Of course it can also be used simply as a term indicating "older than": "I am 25; my sister is 3 years my senior." But that is a more flowery way of speaking.
That's surprising. Where I live I haven't heard "senior citizen" in decades, and most people who become old enough to qualify as senior would be offended to be called elderly, which you might barely qualify as being.
Duolingo should learn to stay away from terms that could be offensive, and claiming that someone old enough to be called a senior in English is elderly isn't appropriate.
Even if it's not the case where you live, that doesn't justify it when there are more neutral words.
Do places where you live still offer senior citizen discounts, and if so, do non-citizens pay more?
Pensioner is not used in America (Canada, the U.S.) because receiving a pension is seen as a form of thievery by a lot of the right-wing types. The British (English, Scottish, . . .) tended to take a different attitude to it; that's all. It sounded like they worked hard and earned their money. I have no idea what the current state of this is -- it always was truly a headache . . .
Mh, yes, but only if you really make clear that you are talking about your schooling system.
There exists neither senior/junior highschool here nor do we differentiate at colleges or universities so much between the different years, so the word
Senior just makes no sense in the context of German schooling.
At our secondary schools, the Gymnasium, a few schools call the most senior class (12 or 13)
ein Schüler der Sekundarstufe II (class 10-12/13) is more common.
I tried "the senior" and "the elder" and both were marked wrong. Is it really so?
Just to point out, "senior" appears as an entry in the Cambridge dictionary and in the Word Reference as well:
The same with "elder":
Does it really sound off to say, without context, in English: "The senior/elder"?
I wrote "the senior" and got it wrong. I am a native English speaker living in USA...once I had this conversation with my father (born/lived in USA with German-speaking immigrated-as-adult parents: Dad: "I'm tutoring seniors in computer technology." Me: "High school seniors or college seniors?" Dad: "Senior-seniors, you know, the gray-haired kind!"