المعنى الاصطلاحي :

The blast coming out the trumpet when Angel Isrāfeel (Uriel) blows into it (on the Day of Judgment) so that people come out of their graves to the gathering place.

الشرح المختصر :

"As-Sayhah" (the Blast) is the blow signaling resurrection from the graves and standing before the Lord of the worlds. It is the sound produced from the trumpet which Angel Isrāfeel will blow into on the Day of Resurrection. It is indicated in the verse: {Then it will be blown a second time and behold, they will be standing, looking on (waiting).} [Az-Zumar: 68] When Allah wills the resurrection of His slaves, He orders Isrāfeel to blow the trumpet. Thereupon, the souls return to the bodies and the people rise to stand before Allah, the Lord of the worlds.

التعريف اللغوي المختصر :

"Sayhah": a loud cry, a thunderous blast; the sound of anything when it becomes loudest and most intense. It also refers to a form of divine punishment.