Definitions
from The American Heritage® Dictionary of the English Language, 4th Edition
 n. A quantum bit.
from Wiktionary, Creative Commons Attribution/ShareAlike License
 n. A quantum bit; the unit of quantum information; a bit in a quantum computer capable of being in a state of superposition.
Etymologies
Examples

Now when I say qubits, I have to stress that the term qubit hasn't got a very precise definition at the moment, and I've been arguing for a long time that the physics community ought to get together and decide on some criteria for different senses for the word qubit.

A small distance (300 nanometers, or 300 billionths of a meter) from the resonator, the scientists fabricated a second nanoscale device known as a singleCooperpair box, or superconducting "qubit"; a qubit is the basic unit of quantum information.

The qubit is the quantum analogue of the bit, the classical fundamental unit of information.

In general, thus, the physical state of a qubit is the superposition

The qubit is the fundamental equivalent of the digital computing "bit."

In contrast, a qubit is a system which can be asked many, many different questions, but to each question, only one of two answers can be given.

(i.e., the qubit is a unit vector in the aforementioned twodimensional Hilbert state), we may

What I mean here is a qubit which is capable of being in any quantum state, and is capable of undergoing any kind of entanglement with another qubit of the same technology, and all those conditions are actually necessary to make a fully fledged quantum computer.

The spin of the electron dictates the value of the quantum bit, or " qubit ."

A quantum bit, or "qubit", is analogous the bits used in conventional computers.
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bilby commented on the word qubit
"Recent experiments with superconducting qubits are motivated by the goal of fabricating a quantum computer, but at the same time they illuminate the more fundamental aspects of quantum mechanics. In this paper we analyze the physics of switching current measurements from the point of view of macroscopic quantum mechanics."
 G. S. Paraoanu, How Do Scrödinger Cats Die?.
June 9, 2009