The most votes in a single preference election. That's the post, that is all that's important. Happy if against convention you want to call it wanky cheese biscuits.
But that isn't a post, as you don't know where it is until after the election. I recognise FPTP is the conventional term used, but it actually makes no sense when you think about it.
We do have genuine FPTP election, both in the UK and elsewhere, where there is a clear post set at 50% - first past this wins. And then you need mechanisms to deal with situations where no-one reaches the post.
In the French presidential election is no-one reaches the post in the first round the top 2 'run off' against each other in a second round, guaranteeing that one of the two will reach the 50% post.
In the London mayoral election there is a variant approach which doesn't require a second round. In that election if no-one reaches 50% all but the top two are eliminated and second choices are reallocated until one candidate reaches the 50% post.
But this isn't what happens in UK constituency elections, where there is no post - it is actually more correctly a plurality-winner system.
You can snide scoff all you like, all I'm doing is discussing things - and in this case thinking about something which I'd always unthinkingly accepted as a term, but with a little more thought is strange. And indeed I suspect you aren't quite clear about it too, nor is HH, in that you can't agree on what the 'post' is - you think it is most votes, he thinks it is 10pm.