Wordnet 3.0
NOUN (1)
1. 
 the expense of maintaining property (e.g., paying property taxes and utilities and insurance); 
 it does not include depreciation or the cost of financing or income taxes; 
[syn: operating expense, operating cost, overhead, budget items]
WordNet (r) 3.0 (2006):
operating expense
    n 1: the expense of maintaining property (e.g., paying property
         taxes and utilities and insurance); it does not include
         depreciation or the cost of financing or income taxes [syn:
         operating expense, operating cost, overhead, budget
         items]