Dinner should also be accepted as this is commonly used in place of lunch, in the UK at least.
If you call "lunch" 'dinner', what do you call "dinner"? -- i.e. the last main meal that you would eat before bed. ¿Tea? ¿Second dinner? :P
Tea would be used in place of dinner, for the evening meal. This is common in the north of England.
But "supper" is used more commonly in some regions than others, and more often by older generations than younger ones.
I don't think supper is only for older generations. It is possibly a class thing, although it pains me to say so, and also as you say, regional.
This has always brought confusion to me since in french we say "dîner" at noon and "souper" around 6pm.
Dinner, in the farm speak, is the main meal of the day. In the farming world; that is "lunch". The evening meal is "supper".
Unless you live in Suffolk, in which case the evening meal is 'tea' - although personally my evening meal is dinner.
Not for me. I'm born and bref uk and i say lunch and dinner not dinner and supper. To me supper is a snack i might or might not have late at night before bed.