Speck (noun)

1. A very small mark or spot.
2. A small amount of a substance.

Origin:

Middle english: from old english specca; related to dutch spek "bacon" and german speck "bacon, lard".

Examples:

1. There was a speck of dirt on her blouse.
2. He had a speck of food on his chin.
3. The speck of paint on the canvas ruined the whole picture.
4. A speck of doubt entered her mind.
5. There was not a speck of dust on the shelves.