Due to corruption of the definition over time, in modern usage "calculus" almost exclusively refers to "The Calculus." The Calculus is also known as "Newton's Calculus," or "Leibniz’s Calculus" depending on who you ask. Mathematics majors tend to refer to The Calculus as "Leibniz’s Calculus" and physics majors tend to refer to The Calculus as "Newton's Calculus.”
Physics Major: "Are you referring to 'Newton's Calculus?'"
Math Major: "I think you mean 'Leibniz's Calculus'"
Physics Major: “No, I mean ‘Newton’s Calculus,’ because Newton slapped Leibniz around like a step-child at Wal*Mart.”
Math Major: sob sob
Dude 2: "Nah dude I got this problem for calc homework that involves differential equations and slope fields, and if I figure it out, my high will be stronger than the high off the strongest chronic"
It is also a name for the page and a half of indecipherable foreplay used in university physics textbooks before they give you the formula for something.
Non-engineering student: I looked in the back of the textbook.
Calculus is not some super-hard subject that only the most brilliant can handle. If you have a good teacher who explains things precisely, you can learn calculus. (Finding such a teacher, unfortunately, can be the hard part.)
Guy 2: Calculus? That sucks.
Guy 1: No it doesn't. I'm finally learning math that I can apply -- you can't be an engineer without it!
Otherwise, should still be taken to make transcript look better.