Wordnet 3.0
VERB (2)
1. 
 take position in the rear, as in a military formation or in the line of scrimmage in football; 
- Example: "The defender dropped back behind his teammate"2. 
 to lag or linger behind; 
- Example: "But in so many other areas we still are dragging"[syn: drag, trail, get behind, hang back, drop behind, drop back]
WordNet (r) 3.0 (2006):
drop back
    v 1: take position in the rear, as in a military formation or in
         the line of scrimmage in football; "The defender dropped
         back behind his teammate"
    2: to lag or linger behind; "But in so many other areas we still
       are dragging" [syn: drag, trail, get behind, hang
       back, drop behind, drop back]