'Interplanetary' definitions:

Definition of 'interplanetary'

(from WordNet)
adjective
Between or among planets; "interplanetary travel"

Definition of 'Interplanetary'

From: GCIDE
  • Interplanetary \In`ter*plan"et*a*ry\, a. Between planets; as, interplanetary spaces; interplanetary travel. --Boyle. [1913 Webster +PJC]