Definition Game
 

Give definition, next person give the word. I'll start

The limiting value of the ratio of the change in a function to the corresponding change in its independent variable.

derivative

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a histopathologic lesion of brain tissue that is characteristic of Alzheimer's disease and consists of a dense proteinaceous core composed primarily of beta-amyloid that is often surrounded and infiltrated by a cluster of degenerating axons and dendrites

plaques ?

Yes, plaque! Now your turn!