1. He is a drunkard.
2. He is a heavy drinker.
3. He is a strong drinker.
4. He drinks like a fish.
5. He is a real soaker.
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There are many expressions about a person who drinks too much in the dictionary. Are they all grammatical? Which ones are commonly used?
Wow, you found a bunch of them! All are correctly written.
The ones most commonly used are 1, 2, and 4, although 3 and 5 are correct, too.
Another expression is "He is an alcoholic," although it's not always used accurately. Here are a few more:
He is drunk.
He is a lush.
He is a boozer.