To jot something down means to write it quickly, usually just a few words to help you remember later. When your teacher mentions an important date, you might jot it in your notebook. When you think of a good idea for a story, you jot it on a scrap of paper before you forget.

The word suggests speed and brevity. You're not writing carefully or completely, just capturing the essential information. A scientist might jot down observations during an experiment. A detective might jot notes about a clue. Your mom might jot items on a shopping list.

Jot can also be a noun meaning a tiny amount, as in “not one jot” or “not a jot of difference.” If something hasn't changed one jot, it hasn't changed even the tiniest bit. This use is less common today but appears in older writing and formal speech.

The quick-writing meaning connects to that sense of smallness: when you jot something, you're writing just a small note, not a whole essay. Think of it as catching an idea before it flies away, writing down just enough to hold onto it.