What is the meaning of Mugger?

A person who assaults and robs others, especially in a public place.

A person who makes exaggerated faces, as a performance; a gurner.

A large crocodile, Crocodylus palustris, of southwest Asia, having a very broad wrinkled snout.

The American Heritage Dictionary of the English Language, 4th edition, Houghton Mifflin Company, 2000

Asko Parpola (2011), “Crocodile in the Indus script and iconography”, in Linguistic Archaeology of South Asia, following Bloch (1930), Turner (1966), and Burrow and Emeneau (1984), the Indo-Aryan etymon derives from the Proto-Dravidian root. Compare Kannada [script needed] (negal), [script needed] (negale, alligator), Tulu [script needed] (negaḷu, alligator), [script needed] (negaru, a sea-animal, the vehicle of Varuṇa), Telugu [script needed] (negaḍu, a polypus or marine animal which entangles swimmers). Parpola suggests the Proto-Dravidian word might derive from the root *neka- (to rise, fly, jump, leap) (DEDR 3730), referring to the crocodile's habit of jumping to catch its victim.

Ganesan, Naga (2011), “A Dravidian Etymology for Makara–Crocodile”, in Prof. V. I. Subramanian Commemoration Volume, Tiruvananthapuram, Kerala: Int. School of Dravidian Linguistics. Compare Hindi, Gujarati, Marathi, and Sindhi [script needed] (magar), Panjabi and Kashmiri [script needed] (magar-macch), Bengali and Nepali [script needed] (makar), Telugu [script needed] (makaramu), Tamil [script needed] (makaram) (in Sangam literature). The transformation from *mokara > [script needed] (makara) occurs because the short vowel phoneme -o- in mokara is not present in Indo-Aryan languages. South Dravidian shows [script needed] (mosale), [script needed] (mosali) (< *mokaray), and Tamil [script needed] (mutalai) (< motalai < mosale) from the same verbal root with -r- > -l- alternation.

N. Ganesan (2018), “Some K-Initial Dravidian Loan Words in Sanskrit: Preliminary Observations on the Indus Language”, in International Journal of Dravidian Linguistics, volume 47, number 2, pages 1-18 notes that "dictionaries trace 'mugger' ultimately to be of Dravidian origin" and provides this as part of evidence that "the most important words for 'crocodile' in South Asian languages have a Dravidian etymology."

comparative form of mug: more mug

Source: wiktionary.org