inarticulate
Unable to speak your thoughts clearly in understandable words.
Inarticulate means unable to express your thoughts and feelings clearly in words. When someone is inarticulate, they might stammer, pause frequently, or struggle to find the right words to say what they mean. It's that frustrating feeling when you know exactly what you want to say in your head, but it comes out jumbled or confusing when you try to speak.
People aren't usually inarticulate all the time. You might be perfectly articulate when talking about your favorite video game, but become inarticulate when trying to explain a complicated math problem or describe why a book made you feel a certain way. Sometimes strong emotions make people temporarily inarticulate: excitement might leave you speechless, or nervousness during a presentation might make your words come out wrong.
The word can also describe the sounds themselves. An inarticulate cry is a wordless sound, like a grunt or moan, that doesn't form actual words. A toddler's babbling is inarticulate because they haven't yet learned to form clear words.
The opposite is articulate, which describes someone who speaks clearly and expressively. People often become more articulate with practice, and reading widely and saying things out loud can help you express yourself more clearly.