Lock Step refers to any of dance steps which involves the "locking" of the moving foot: the moving foot approaches to the standing foot, crosses in front of or behind it in the direction of the approach, stops close to the standing foot, and the weight is fully transferred to the (previously) moving foot.

The closeness of the feet so that the lower legs of the dancer are "locked" together crossed is the main difference from other cross-steps used, e.g., in the Grapevine

Grapevine (dance move)

Grapevine is the name of a dance figure, which may look different in various ballroom, club, and folk dances, but shares a common appearance: it includes side steps and steps across the support foot.-Sequence:...

, where the moving (crossing) foot travels away from the standing foot and the lower legs are separated. In the Whisk the crossing foot travels around the standing foot, rather than "locks" from the direction of approach.

The term "lock step" or simply "lock" may be applied either to a single "locking" step or to a whole step pattern, e.g., of three steps, such as "step diagonally forward, lock behind, step diagonally forward". The footwork varies depending on the actual dance figure.

Lock steps are popular in Quickstep

Quickstep

The quickstep is a light-hearted member of the standard ballroom dances. The movement of the dance is fast and powerfully flowing and sprinkled with syncopations. The upbeat melodies that quickstep is danced to make it suitable for both formal and informal events...

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Ballroom dance figures

There are several dance figures with names involving the words "lock" or "lock step", as well as several figures that use the lock as part of the pattern.

• Backward Lock Step (Backward Lock, Back Lock)
• Forward Lock Step (Forward Lock)
• Turning Lock
• Curving Lock
• Skip Lock
• Syncopated Lock (single or double)
• Samba Locks
• Cruzados Locks
• The Six Quick Lock
• Double Lock
• Forward Checked Lock

• Reverse turns in Viennese Waltz
  Viennese Waltz
  Viennese Waltz is the genre of a ballroom dance. At least three different meanings are recognized. In the historically first sense, the name may refer to several versions of the waltz, including the earliest waltzes done in ballroom dancing, danced to the music of Viennese Waltz.What is now called...
  
  
• Fishtail
• In Cha-cha-cha
  Cha-cha-cha (dance)
  The Cha-cha-cha is the name of a dance of Cuban origin.It is danced to the music of the same name introduced by Cuban composer and violinist Enrique Jorrín in 1953...
  
  , advanced variations of basic figures may involve replacement of the cha-cha-cha chasse
  Chasse
  Chasse or chassé rarely chassée is a dance step used in many dances in many variants, all of them being triple-step patterns of gliding character, steps going basically step-together-step. The word came from ballet terminology...
  
  s with the lock-steps.
• Some Triple Step
  Triple Step
  Triple Step is a generic term for dance step patterns that describes three steps done on two main beats of music. Usually they are two quick steps and one slow one, i.e., often they are counted as "quick-quick-slow", "one-and-two", "three-and-four", etc....
  
  s in West Coast Swing
  West Coast Swing
  West Coast Swing is a partner dance with roots in Lindy Hop. It is characterized by a distinctive elastic look that results from its basic extension-compression technique of partner connection, and is danced primarily in a slotted area on the dance floor...
  
  may be stylized into lock-steps.