Definition of internuncial in English:
internuncial
adjective ˌɪntəˈnʌnʃ(ə)lˌintərˈnənsēəl
Physiology (of neurons) forming connections between other neurons in the central nervous system.
Origin
Mid 19th century: from Latin internuntius (from inter- 'between' + nuntius 'messenger') + -al.