I have difficulty understanding the exact difference between these two adjectives, semantically. This is quote from a native English speaker:
Parasite single? I guess an embittered parent wrote that one.
Why has the author written embittered instead of bitter? Is a different adjective used for a human and an object?
A person who is embittered was made bitter, as opposed to being transiently bitter for some reason or another. The use of embittered in this sentence suggests that the parent has a particular ax to grind with whatever institution the speaker belongs to.
I had to go to three dictionaries before I found one that gave credence to my understanding of the distinction between "bitter" and "embittered", but at Cambridge's online dictionary, there is this definition:
embitter, v. to make someone feel angry and unhappy for a long time
So the difference between someone who is bitter and someone who is embittered is that the bitter person is bitter about some specific thing right now, while the embittered person is consistently bitter (and is likely to express their bitterness on a variety of matters), has probably been bitter for a long time, and shows no signs of relenting from their habitual bitterness.
I guess that the difference between the two terms is that we can use embittered for something for which we look and feel their effects; vice versa, we can use bitter with a wider range.
It is possible but uncommon to describe a non-sentient thing as being embittered. Some recipes call for adding bitter flavors to a food or drink, so if a recipe called for adding lemons to a soup, you could say "That soup was embittered with lemon."
