Wordnet 3.0
NOUN (2)
1. 
 the time between occurrences of a repeating event; 
- Example: "some women do not control the spacing of their children"2. 
 the property possessed by an array of things that have space between them; 
[syn: spacing, spatial arrangement]
WordNet (r) 3.0 (2006):
spacing
    n 1: the time between occurrences of a repeating event; "some
         women do not control the spacing of their children"
    2: the property possessed by an array of things that have space
       between them [syn: spacing, spatial arrangement]