20 April 2014
Of course your elbow is the middle part of your arm that separates your upper and lower arm and bends. Grease, which comes from the same root as the French word graisse, is a thick substance similar to oil that is used on machine parts to help make them work more smoothly.
To use elbow grease is a humorous, idiomatic term used for situations when some tasks can only be accomplished by hard, physical effort. It is often used when hard physical work is required when cleaning something, such as burned food on a baking dish.
In the image above, you find another good idiomatic expression: to roll up your sleeves.
A sleeve is the part of clothing that covers the arms, and often the image of rolling them up is an image of preparing for some hard work. You might hear someone say, "It's time for us to roll up our sleeves and get down to work."
Posted by Joseph BOËN, formateur d'anglais et coordonateur pour les formations en anglais au Greta Nord Alsace, HAGUENAU France on Sunday, April 20, 2014