For instance, a cup of cappuccino was made with too much water and because of it its taste was not that strong. What are correct words to say it? Dictionary returns many options, but which ones are the most appropriate for given context?
Cappuccino is diluted | washy | watered | poor and weak | soft | mild?
As a speaker of American English, I would use the word weak to refer to the kind of coffee you describe.
I might also call it watery or watered-down, but, while they mean the same thing, they're less common than weak in these circumstances.
When I used to help out in an Italian family-run restaurant in London, the coffees ordered by American tourists were either called acqua sporca ("dirty water") or acqua nera ("black water") by the waiters. Nowadays, long black coffees served in Italian restaurants might be called American coffee, or a long black.
As for cappuccinos, if too much water (or milk) has been added, just say the beverage tastes more like weak white coffee than a proper Italian cappuccino.
Cappuccino is diluted. Cappuccino is poor and weak.
we can use both sentences.
