interstellar

from WordNet (r) 3.0 (2006)

interstellar
    adj 1: between or among stars; "the density of hydrogen in
           interplanetary and interstellar space"

from The Collaborative International Dictionary of English v.0.48

Interstellar \In`ter*stel"lar\, a.
   Between or among the stars; as, interstellar space. --Bacon.
   [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

48 Moby Thesaurus words for "interstellar":
      Cynthian, anagalactic, asteroidal, astral, astrologic,
      astrologistic, astrologous, astronomic, astrophysical, celestial,
      circumplanetary, cislunar, empyreal, empyrean, equinoctial,
      extragalactic, galactic, heavenly, heliacal, intercosmic,
      interplanetary, intersidereal, lunar, lunary, lunate, lunular,
      lunulate, meteoric, meteoritic, nebular, nebulose, nebulous,
      planetal, planetarian, planetary, planetesimal, semilunar,
      sidereal, solar, sphery, star-spangled, star-studded, starry,
      stellar, stellary, terrestrial, uranic, zodiacal