Why is the noun 'sex' uncountable? [closed]

According to the definition of the noun 'sex' in dictionaries, it means 'the PHYSICAL ACTIVITY that two people do together in order to produce babies or for pleasure.' If so, why isn't it countable?

'I had sex with her last night.' but not 'I had A sex / TWO sexes her last night.'

How do you count the activity? You go like 'I had sex with her twice.'?

I think that in general, a countable noun has a beginning and an end, viewed as a whole entity, while an uncoutable noun is undifferentiated and lacking in defined limits. Could the activity of sex continue no end? It must have a beginning and an end. The human can't do it forever even if he was cut out for it. Just saying the word is in itself an uncountable noun is a circular logic.

You could have A shag with her if you ask her out tomorrow.

why is 'shag' countable, while 'sex' is not? Both seem to refer to the same activity.

You say

• Let's go for a drive.
• I take a shower every day.
• I had a walk in the morning.
• I'm going for a stroll.

All the nouns refer to activities, and are used with the indefinite article.

I really want to know what you have in mind about the interesting noun 'sex' and the reason why it isn't countable.

Your analysis is strictly logical. Language is not strictly logical. I've been fighting that battle with myself all my life.

The answer to your question is that sex is a noncount noun because native Anglophones treat it as a noncount noun and use it as a noncount noun. That's idiomatic English, like it or not, logical or not.

Do you have a reference that says "You could have a shag with her" is possible in English? I don't use the word myself, but the verb to shag is a synonym for to have sex. If I were to use it, I would undoubtedly say "You could shag her if you asked her out tomorrow", not "You could have a shag with her": that sounds unnatural to me.