Ylide Definition: A ylide (pronounced ill-id) is a neutrally polar molecule formed by bonding an negatively charged atom to a positively charged heteroatom where both atoms have a full octet of electrons.
Alternate spelling: ylid
Methylene(triphenyl)phosphorane is a ylide molecule. Ylides are often depicted by a ylide resonance structure similar to the one in the image. The right hand structure is known as the ylide form showing the net charges at the ylide bond.