That is what I have been saying all along!
I know that. I am saying that by continuing to use the
old definition of meat, people are inadvertedly making life harder for vegetarians as restaurants and many people seem to assume I still eat fish.
That’s what I’ve been asking!

/QUOTE
I thought that might be it.
It’s a question of semantics.
All you have to do is say that the Church’s rule of abstinence pertains to all meat except fish, which is permitted because ancient understanding exempted ‘cold blooded’ animals’, but that of course all who are vegetarians would not eat fish anyway.
Because the Church’s rules were not created for vegetarians. . .or carnivores. They were created for all people. Some people never ate meat of warm or cold blooded creatures anyway. Some people always ate meat but never fish; some ate fish but never other meat.
It reminds me in a way of the Eucharist being wine and wheat bread (unleavened in the West and leavened in the Orthodox). Celiacs cannot eat gluten (which is always found in wheat), and alcoholics cannot take wine, even the mustum, but we hold to the ‘ancient’ definitions of ‘wheat bread’ and ‘wine’. That’s why we don’t make rice or corn bread both of which in modern definition would be considered bread. And lots of people would say that ‘wheat bread’ could contain other things than flour and water. . .such as milk, eggs, soda. . .and still be ‘wheat bread’ by the modern definition.
The Church teaches for all time, and so we can’t just accept the ‘modern’ definition.
If we did, we would have to jettison centuries’ worth of teaching about prayer and worship, because ‘prayer’ and ‘worship’ did not mean the same thing ‘then’ as the ‘modern’ definition held by most people teaches today.
So I sympathize because yes, I know that by today’s definition of meat, fish is ‘meat’ just as much as chicken and pork –
and yes, I usually say "the Church’s rule of abstinence is from that of meat of warm-blooded creatures, but fish did not USE to be considered in the same class and is permitted so long as you’re not a vegetarian’,
But I would not insist that the Church ‘change’ the teaching and have to ‘redefine’ meat for the modern day understanding.
For all that I know, somebody will discover 100 years from now that there is something ‘different’ from the meat of warm blooded creatures and cold blooded creatures such that they are as different in substance from each other as chalk and cheese, and will indeed redefine meat as ‘fowl and warm blooded creature’ and flesh from cold-blooded creatures as, oh, we’ll call it 'pisca" (related to the Latin for fish). It could happen. Then people would be surprised that ‘pisca’ was ever lumped in with meat!