The Collaborative International Dictionary of English v.0.48:

jocose \jo*cose"\ (j[-o]*k[=o]s"), a. [L jocosus, fr. jocus
   joke. See Joke.]
   Given to jokes and jesting; containing a joke, or abounding
   in jokes; merry; sportive; humorous.
   [1913 Webster]

         To quit their austerity and be jocose and pleasant with
         an adversary.                            --Shaftesbury.
   [1913 Webster]

         All . . . jocose or comical airs should be excluded.
                                                  --I. Watts.

   Syn: Jocular; facetious; witty; merry; pleasant; waggish;
        sportive; funny; comical. -- jo*cose"ly, adv. --
        jo*cose"ness, n.
        [1913 Webster]

              Spondanus imagines that Ulysses may possibly speak
              jocosely, but in truth Ulysses never behaves with
              levity.                             --Broome.
        [1913 Webster]

              He must beware lest his letter should contain
              anything like jocoseness; since jesting is
              incompatible with a holy and serious life.
                                                  --Buckle.
        [1913 Webster]

WordNet (r) 3.0 (2006):

jocoseness
    n 1: the trait of merry joking [syn: jocoseness, jocosity,
         merriness, humorousness]