Synonyms for Spiritless (same or very similar meaning)
WordNet sense 1 (marked by low spirits; showing no enthusiasm):
listlessWordNet sense 2 (showing little or no emotion or animation):
apatheticWordNet sense 3 (evidencing little spirit or courage; overly submissive or compliant):
meekWordNet sense 4 (inclined or willing to submit to orders or wishes of others or showing such inclination):
submissiveFrom the ODE community, based on WordNetadd/edit