The Collaborative International Dictionary of English v.0.48:

Lunisolar \Lu"ni*so"lar\, a. [L. luna moon + E. solar: cf. F.
   lunisolaire.]
   Resulting from the united action, or pertaining to the mutual
   relations, of the sun and moon.
   [1913 Webster]

   Lunisolar precession (Astron.), that portion of the annual
      precession of the equinoxes which depends on the joint
      action of the sun and moon.

   Lunisolar year, a period of time, at the end of which, in
      the Julian calendar, the new and full moons and the
      eclipses recur on the same days of the week and month and
      year as in the previous period. It consists of 532 common
      years, being the least common multiple of the numbers of
      years in the cycle of the sun and the cycle of the moon.
      [1913 Webster]

WordNet (r) 3.0 (2006):

lunisolar
    adj 1: relating to or attributed to the moon and the sun or
           their mutual relations