Wordnet 3.0
NOUN (1)
1. 
 ancient Greek philosopher who succeeded Zeno of Citium as the leader of the Stoic school (300-232 BC); 
WordNet (r) 3.0 (2006):
Cleanthes
    n 1: ancient Greek philosopher who succeeded Zeno of Citium as
         the leader of the Stoic school (300-232 BC)