A set of words and rules that we make errors in our daily English uses.

Example:

dairy / diary - A common typo that won’t be caught by your spelling checker is swapping “dairy” and “diary.” Butter and cream are dairy products; your journal is your diary.

damped / dampened - When the vibration of a wheel is reduced it is damped, but when you drive through a puddle your tire is dampened. “Dampened” always has to do with wetting, if only metaphorically: “The announcement that Bob’s parents were staying home after all dampened the spirits of the party-goers.” The parents are being a wet blanket.