The disorder of two people who aren't literally twins, but they act the same, think the same, and very often say the same thing at the same time. Many times these people are complete opposites in their appearance.
House of Night, Erin Bates and Shaunee have definite twinititus, but they're also called Twins by the people around them and call each other Twin.
by BrittaQuinnGleeLover June 17, 2010