A speck is a tiny patch or spot. At night, the stars look like glittering specks against the sky. And when you look up at the night sky, you might feel like a mere speck in the universe.
A speck is a bit of color or light, or a very slight amount of something: "I'd like my eggs with lots of salt and just a speck of pepper." If you're extremely tidy, discovering specks of sand on your jeans after a walk on the beach might prompt you to change your clothes. Speck can be traced back to the Old English specca, "small spot or stain," but beyond that its origin remains a mystery.