speck
/spek; spɛk/ n
very small spot or stain; tiny particle (of dirt, etc) 小斑点; 小污点; （泥土等的）小颗粒
a speck of soot on his shirt 他衬衫上的黑炱斑
Do you ever see specks in front of your eyes? 你是否有过眼前出现黑斑的现象?
The ship was a mere speck on the horizon. 那只船在天水交接处不过是一个小点儿.