Ada yang katakan namanya adalah singkatan dari Muara. Ekstrak dari wiki ini pula dinyatakan pelbagai teori.
Muar also known as Bandar Maharani is said to have had other names earlier and the name itself Muar is believed to have originated and derived from its geographical location at the mouth or estuary of Muar River as the following different version of theories:
Teluk Dalam :Muar was formerly known as Teluk Dalam meaning "the deep bay" may be derived from its location at the estuary or the structure of the mouth of the Muar River which is wide open and deep; based on a sentence in one part of Hikayat Malim Deman; as in :-
MUAR belum bernama MUAR , MUAR bernama TELUK DALAM.
(MUAR has not been named MUAR , MUAR called TELUK DALAM.)
Muara :Muar name is said to be the summary for this old Malay word Muara meaning "the wide open estuary".
Muak :Means "bored" or "tired" in paddling the boat travelling along the river which is large and curvy by the local people in the early days. The people started calling the river and place Muar deriving from the word Muak after a long time since then.
Munu-AR/Muar/Munar/Mu-aru :Muar may be a combination of the Sanskrit Hindu language words Munu meaning "three" and Ar which means "river". The old Tamil word Mu-Aru also means three rivers. There was a large state in South India which three important rivers merged into a river called Muar or Munar('Three Rivers State'). When the Indians traders came to the country to trade and look for gold during ancient times, they found the three rivers; the Sungai Muar, Sungai Serting and Sungai Pahang met and merged into Sungai Muar just like in the state of Munar in India, thus the river took the name Muar as from the name of Munar in India. The Muar name is said to be derived from these words and names.
Bukit Mor :There is also a hill not far from the Muar near Parit Jawa in the south of the "Padang" area called Mor Hill or Bukit Mor which may be the origin of the name of Muar.
Bandar Maharani :Modern Muar Town as officially opened and conferred Bandar Maharani title by Maharaja Abu Bakar translated as the Town of Empress the namesake of Maharani Fatimah who also graced the grand inauguration ceremony of the new town on 12 August 1887, to symbolically representing and recognizing the prominence status of Muar as the 2nd important and biggest town and district of the state of Johor after Johor Bahru the capital city in those days.
There a few famous old historic legends which evolved around the area of Muar namely, Hikayat Malim Deman (Epic of Malim Deman), Legenda Lembing Awang Pulang Ke Dayang (Awang's Spear Return to Dayang Legend) and Legenda Puteri Gunung Ledang (Mount Ledang Princess' Legend).
Pernahkah saudara melawat ke Portugis atau bersembang dengan orang Eropah yang dahulu pernah bersekutu dengan kaum penjajah,
Dahulunya, semua orang Islam dipanggil 'Moor' hingga sekarang. Orang Islam mindanao juga dipanggil Moro.
Semasa kejatuhan empayar Melaka, sekumpulan pendekar dan pahlawan Melayu telah berpindah beroperasi dari seberang sungai di Selatan Melaka. Mereka ini masih dipanggil 'Moor' selepas kejatuhan kota Melaka.
Sebutan 'Muar' oleh orang2 tempatan adalah unik dan agak seakan dengan sebutan 'Moor' oleh orang Portugis, Sepanyol dan Inggeris.
Inilah sebenarnya asal usul bandar Muar atau 'Moor'.