The term “addlebrain” is a rather informal and somewhat archaic way to describe someone who is confused or not thinking clearly. Here are some synonyms that can be used in more modern contexts:
“confused soul” implies a person who is bewildered and not able to make sense of things. For example, “He seemed like a confused soul, unable to decide which path to take.” This description gives a more sympathetic tone compared to “addlebrain”.
“muddled thinker” suggests someone whose thoughts are jumbled and not organized. For instance, “The muddled thinker couldn’t come up with a coherent plan.” It emphasizes the lack of clarity in thinking.
“befuddled person” conveys a sense of being completely perplexed. For example, “The befuddled person stared blankly at the complex instructions.” This synonym highlights the state of being utterly confused.
“dazed individual” implies a person who is in a state of shock or confusion, as if they have been stunned. For example, “The dazed individual wandered around, not knowing where to go.” It gives a more vivid picture of someone who is not functioning at their best mentally.