Glossary entry (derived from question below)
English term
sleepers
Proposed translations
Germany
professional and timely manner
Native in: Arabic (Variants: Sudanese, Egyptian, Lebanese, Palestinian, Yemeni, Saudi , UAE, Standard-Arabian (MSA), Moroccan, Syrian, Libyan, Kuwaiti, Algerian, Jordanian, Tunisian, Iraqi) 
Works in: English to Arabic, German to Arabic, Arabic
مشرديين
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"ٍsleepers"in other contexts could also mean خلايا نائمة
A sleeper (agent) is a spy who is placed in a target country or organization not to undertake an immediate mission but to act as a potential asset if activated.
https://en.wikipedia.org/wiki/Sleeper_agent
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Note added at 23 mins (2019-06-20 00:25:09 GMT)
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https://www.alamy.com/stock-image-rough-sleeper-homeless-per...
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Note added at 25 mins (2019-06-20 00:26:27 GMT)
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https://www.nao.org.uk/naoblog/growing-number-of-rough-sleep...
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Note added at 25 mins (2019-06-20 00:27:02 GMT)
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https://www.straight.com/life/1087231/homeless-vancouver-eti...
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Note added at 49 mins (2019-06-20 00:51:02 GMT)
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Dragsters,sleepers , drifters and outlaws
هؤلاء جميعهم أشخاص و هم يقومون بالتحريض واحدهم ضد الآخر
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Note added at 20 hrs (2019-06-20 21:00:48 GMT)
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مشرد أو متشرد
Egypt
Quality is my Sales Agent
Native in: Arabic
Works in: English to Arabic, Arabic to English
عارضة
الكسالى / العاطلون
Egypt
Best translation at the lowest Prices
Native in: Arabic
Works in: English to Arabic, Arabic to English, German to Arabic, and 13 more.
متشردون
| Thank you. |
السَيَّاراتُ المُعَدَّلَةُ الأداء
Sleeper (car), an automobile that has been modified to improve its performance without changing its outward appearance; the British term for this is Q-car
https://en.wikipedia.org/wiki/Sleeper
عربات نوم
(also sleeper)
noun
a railway/railroad carriage with beds for people to sleep in
Longman Dictionary of Contemporary English
sleeping car
'sleeping car noun [countable]
a railway carriage with beds for passengers to sleep in SYN sleeper
Egypt
Accuracy Matters!
Native in: Arabic (Variants: Lebanese, Syrian, Standard-Arabian (MSA), Sudanese, Egyptian, Saudi , UAE)
Works in: English to Arabic, Arabic to English, Arabic
عارضات/عربات النوم
Canada
translation, subtitling, localization
Native in: Arabic (Variants: Iraqi, Standard-Arabian (MSA))
Works in: English to Arabic, Arabic to English
Discussion
https://en.wikipedia.org/wiki/Dragster_(car)
A sleeper (US English) or Q-car (British English) is a car that has high performance and an unassuming exterior. Sleeper cars are so called because their exterior looks similar or identical to a standard or economy-class car.
https://en.wikipedia.org/wiki/Sleeper_(car)
Drifting is a driving technique where the driver intentionally oversteers, with loss of traction in the rear wheels or all tires, while maintaining control and driving the car through the entirety of a corner. The technique causes the rear slip angle to exceed the front slip angle to such an extent that often the front wheels are pointing in the opposite direction to the turn (e.g. car is turning left, wheels are pointed right or vice versa, also known as opposite lock or counter-steering).
https://en.wikipedia.org/wiki/Drifting_(motorsport)
Outlaws
The World of Outlaws (often abbreviated WoO) is an American motorsports sanctioning body. It is best known for sanctioning a national tour of sprint cars called the World of Outlaws Sprint Car Series.
https://en.wikipedia.org/wiki/World_of_Outlaws