In a scattered, unfocused, or inconsistent manner; jumping from one thing to another without a clear plan or purpose.
From 'desultory' (meaning scattered or disconnected) plus the adverb suffix '-ly.' Traces back through Latin to the Roman circus performers who jumped between horses.
When you're studying 'desultorily,' you're basically reading a math chapter, then history, then checking your phone—the word perfectly captures that scattered, jumping-around feeling that kills productivity.
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