lag1
  
  v.
 (lags, lagging, lagged)
  - fall behind; follow after a delay.
- N. Amer. another term for string (in sense 6).
n.
 
(also 
time lag)
 a period of time between two events; a delay.
Derivative
  
  Etymology
  C16 (as n. in the sense ‘hindmost person’): rel. to the dial. adj. lag (perh. from a fanciful distortion of last1, or of Scand. origin).
 
  
    
lag2
  
  v.
 (lags, lagging, lagged)
 enclose or cover (a water tank, pipes, etc.) with insulating material.
Derivative
  
  Etymology
  C19: from earlier lag ‘piece of insulating cover’.