calculus

noun

1
the branch of mathematics that is concerned with limits and with the differentiation and integration of functions
2
a hard lump produced by the concretion of mineral salts; found in hollow organs or ducts of the body
renal calculi can be very painful
3
an incrustation that forms on the teeth and gums

Also useful for “calculus”:Unscrambler— Rearrange the letters in “calculus”