Untie  To Verb Untied  Untied Free Tie Knot

Merriam-Webster's Collegiate Dictionary

 DATE  before 12th century

untie
  O.E. untiegan, from un- (2) + tie (v.).

untie
untie / Qn5tai / verb[VN]
   to undo a knot in sth; to undo sth that is tied
   解开…的结；打开:
   to untie a knot 
   解开绳结 
   I quickly untied the package and peeped inside. 
   我迅速拆开包裹,往里瞥了一眼。 
   He untied the rope and pushed the boat into the water. 
   他解开缆绳,把小船推入水中。 

un·tie
\“+\ verb
Etymology: Middle English untyen, from Old English untīegan, from un- (II) + tīegan to tie — more at 
transitive verb
1. : to detach from something by loosing a connecting rope or other tie
 < untied the horse from the fence >
2. : to free from something that fastens or restrains : let loose : 
 < untied him from his promise >
specifically : to set free from a rope or other confining bond
 < untied his hands >
 < untied the package >
3. 
 a. : to disengage the knotted parts of
  < untied his tie, took it off, and opened his collar >
  < found it hard to untie the knot >
 b. : , 
  < the worst traffic tangle … when 75,000 cars choked all roads leading out of the city, was untied — Sydney (Australia) Bulletin >
 c. : , 
  < untie the spell — Shakespeare >
intransitive verb
1. : to become loosened or unbound
 < all cords easily untied but the one binding me to what I loved — Anais Nin >
2. : to unfasten a knot or loosen a bond
 < those who tangled must untie — Robert Browning >