When reading a passage, I found that I didn’t understand the word “altogether” well, so looked it up in the OALD and the Genius English-Japanese Dictionary.
One example in the OALD was “I’m not altogether happy (= I’m very unhappy) about the decision”. This confused me because I’ve heard that “not always/necessarily/completely/everything etc.” doesn’t mean “never/not at all”.
On the other hand, one example in the Genius was “That is not altogether bad (=That is fairly good)”. This is usual to me, so I searched for questions about this and found similar one in this site. In a comment, “not altogether happy” was one example that doesn’t imply partially because the speaker is deliberately understating.
So I think “not altogether happy” is a fixed expression in a sense.
I’d like to know other examples in which “not altogether” means “not at all”.