Here's from the movie The Enemy Below(1957). You can watch it on youtube.


Echo faded. I've lost contact.

Lewis can't find him, sir.

Secure underwater search.

Reduce speed to two-thirds.

Secure underwater search. Reduce speed to two-thirds.

What does "Secure underwater search" mean? It is clear what "underwater search" means, but I'm not sure what the "secure" means.


'Secure' in this sense means to safely put away or end. It's usually used, as you've discovered, in a military environment. For example, were you a soldier, you may be told to secure your weapon - i.e. put the safety catch on and point it at the ground.

So here, the sonar operator is being told to stop his underwater search.

  • +1 as this seems to be the correct explanation, but applying this to a sonar system seems like a misuse of the word "secure". As you say, securing a weapon means not just stopping using it but making it safe. By analogy, securing the sonar system would normally mean, for example, switching it off and locking the room it's in so nobody can get to it. If "secure" is used by the military (whose, by the way?) to mean just "stop", it's military jargon that's not in general use. – David Richerby Sep 29 '14 at 7:57
  • @DavidRicherby I think it's more a naval thing; in the cramped conditions on board ship, anything you weren't using would need to be stored away. "Secure from general quarters" appears to be a standard order. – richardb Sep 29 '14 at 8:57

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