joint probability

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The probability that two or more specific outcomes will occur in an event.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The probability distribution of a random variable whose sample space is the Cartesian product of the sample spaces of its (at least two) component random variables.
• noun The probability that two events will occur simultaneously.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the probability of two events occurring together