Definition of predissociation in US English:

predissociation

noun

Chemistry Physics
  • The passage of a molecule between a quantized vibrational and rotational state (above its ground state) and an unquantized dissociated state of the same energy, resulting in certain bands in the spectrum of the molecule being diffuse instead of having the normal rotational fine structure.

Origin

1920s. From pre- + dissociation; apparently coined by V. Henri and M. C. Teves.