Details:
Etymology. Originally ‘a royal residence’, that is ‘palace’ or ‘royal camp’ as the circumstances demanded; In Azerbaijani and Ottoman Turkish it came to mean ‘a royal camp’, thence any ‘military camp’ and finally, in military terminology, the largest type of military formation, ‘army’ — elsewhere it retained its original meaning, but there are indications that in some languages it was reborrowed from Mongolian (Clauson, 1972). Erdal (1991) hypothesises that it is derived from a reconstructed verb or- meaning that orun (“place”) and ortu (“middle”) as sharing the same root.
Borrowings into other languages. The Turkic word ordu “royal camp, palace; army, camp” was widely borrowed into other languages: Classical Mongolian ᠣᠷᠳ᠋ᠤ (ordu) and modern Mongolian орд (ord); Classical Persian اُرْدُو (urdū), with descendants or further borrowings in Dari اُرْدُو (urdū), Iranian Persian اُرْدُو (ordow), Tajik урду (urdu) / Урду (Urdu), Bengali উর্দু (urdu), French ourdou, Gujarati ઉર્દૂ (urdū), Hindi उर्दू (urdū), Urdu اُرْدُو (urdū), English Urdu, Nepali उर्दु (urdu) / उर्दू (urdū), Odia ଉର୍ଦୁ (urdu) / ଉର୍ଦୂ (urdū), Kannada ಉರ್ದೂ (urdū), Marathi उर्दू (urdū), Punjabi Gurmukhi ਉਰਦੂ (uradū), Punjabi Shahmukhi اُرْدُو (urdū), and Telugu ఉర్దూ (urdū). It is also connected with Xiong-nu > Old Chinese 甌脫 (ōutuō), Kalmyk орда (orda), Middle French horde, German Horde, Polish horda, Russian орда (orda), English horde, Macedonian орда (orda), Albanian hordhi, Northern Kurdish ordî, Arabic عُرْضِيّ (ʕurḍiyy), Amharic ዕርድ (ʿərd), Tigre ዕርዲ (ʿərdi), and Tigrinya ዕርዲ (ʿərdi).