العالم
كلمة (عالم) في اللغة اسم فاعل من الفعل (عَلِمَ يَعلَمُ) والعلم...
Praying the four-"rak‘ah" (unit of prayer) prayer as only two "rak‘ahs" while on a journey.
"Qasr-us-salāh" (shortening the prayer) means reducing the four-"ra‘kah" prayer to two "rak‘ahs" during travel, in both safe and unsafe circumstances. This practice was legislated in the fourth year after "Hijrah" (emigration).
To offer a 4-rakꜤah prayer in two RakꜤahs, for a reason, such as travelling. It is also called taqṣīr al-ṣalāh, but this is rare.