##### Wiktionary

**molecular orbital**

n. (context quantum chemistry English) The quantum mechanical behaviour of an electron in a molecule describing the probability of the electron's particular position and energy; approximated by a linear combination of atomic orbitals.

##### Wikipedia

**Molecular orbital**

In chemistry, a **molecular orbital** (**MO**) is a mathematical function describing the wave-like behavior of an electron in a molecule. This function can be used to calculate chemical and physical properties such as the probability of finding an electron in any specific region. The term *orbital* was introduced by Robert S. Mulliken in 1932 as an abbreviation for *one-electron orbital wave function*. At an elementary level, it is used to describe the *region* of space in which the function has a significant amplitude. Molecular orbitals are usually constructed by combining atomic orbitals or hybrid orbitals from each atom of the molecule, or other molecular orbitals from groups of atoms. They can be quantitatively calculated using the Hartreeâ€“Fock or self-consistent field (SCF) methods.