An Etymological Dictionary of Astronomy and Astrophysics

A compound → proposition in which one → clause asserts something as true provided that the other clause is true.
A conditional statement consists of two parts, a hypothesis in the “if” clause and a conclusion in the “then"clause. For instance, “If it rains, then they cancel school.”
It rains is the hypothesis. “They cancel school” is the conclusion. The clause following if is traditionally
called the → antecedent, whereas the clause following then is called the → consequent.

See also: → conditional; → proposition.