Here are some key terms in calculus:

1. Limit: The value that a function approaches as the input approaches a certain point.

2. Derivative: A measure of how a function changes as its input changes; represents the slope of the tangent line.

3. Integral: A mathematical object that represents the area under a curve; can be definite or indefinite.

4. Function: A relation between a set of inputs and a set of possible outputs.

5. Continuity: A property of a function if it is uninterrupted or unbroken over an interval.

6. Chain Rule: A formula for computing the derivative of the composition of two or more functions.

7. Product Rule: A formula used to find the derivative of the product of two functions.

8. Quotient Rule: A method for finding the derivative of a quotient of two functions.