Source : WordNet®

let loose
     v 1: express audibly; utter sounds (not necessarily words); "She
          let out a big heavy sigh"; "He uttered strange sounds
          that nobody could understand" [syn: {utter}, {emit}, {let
          out}]
     2: turn loose or free from restraint; "let loose mines"; "Loose
        terrible plagues upon humanity" [syn: {unleash}, {loose}]