Pollen is the very fine powder that flowers make. Wind or insects carry it to another flower of the same kind, and that is how the plant can make seeds. You cannot see one grain with your eye; a cloud of it looks like dust, often yellow. People with hay fever feel it in spring. Bees pack it on their legs. A scientist in the 1700s, Linnaeus, took the old Latin word pollen, which meant fine flour, and used it for this flower-dust — so the 'flour' picture is still sitting inside the name. It is usually uncountable: some pollen, a lot of pollen, not 'many pollens' in everyday talk. There is a rare verb to pollen, but almost everyone says pollinate for the action.