What does the word "kangaroo" translate as, literally?

When European explorers were first in Australia, they saw these strange looking animals hopping around. They asked the natives (Aborigines) what they were called and they answered 'kangaroo' meaning 'I don't understand' your question. The Europeans thought that was the name of the animal and the rest is history.

The name kangaroo came from the Aborigines through a mistake. An early European explorer asked an Aborigine what these strange hopping animals were, and the Aborigine replied kangaroo, meaning "I don't understand." The explorer thought he was naming the animal.

https://www.ferris.edu/HTMLS/news/card/Kids_Corner/marsupials.htm

The above is a myth. See post below, and this webpage:

Linguists have recently discovered that "Kangaroo" does NOT mean "I don't know", it actually means "kangaroo".

https://www.reddit.com/r/australia/comments/8xvhz1/linguists_have_recently_discovered_that_kangaroo/

From the much-maligned Wikipedia we get...

"The word 'kangaroo' is said to derive from the Guugu Yimidhirr (an Australian Aboriginal language) word 'gangurru,' referring to the Grey Kangaroo. The name was first recorded as 'kangaru' by Joseph Banks on James Cook's first voyage of exploration, when they were beached at the mouth of the Endeavour River in the harbour of modern Cooktown for almost 7 weeks repairing their ship which had been damaged on the Great Barrier Reef.

'Kangaroo' soon became adopted into standard English where it has come to mean any member of the family of kangaroos and wallabies."

https://en.wikipedia.org/wiki/Kangaroo

The following contains a discussion about the famous "I don't understand" story regarding the kangaroo:
http://www.straightdope.com/classics/a2_236.html
A charming legend has been making the rounds for many years that the word "kangaroo" derives from an aboriginal expression meaning "I don't understand you." Seems the English explorer Captain James Cook was browsing around Australia one day with his naturalist buddy Sir Joseph Banks, when he happened to espy a funny-looking critter with a pouch. Inquiring of a nearby local as to the name of the animal, he received the reply "kangaroo," which was intended to signify "say what?" Cook somewhat stupidly construed this as the name of the beast, and we have continued to suffer for his ignorance down to the present day. Cute, but is it true? I dunno — the actual aboriginal words for the marsupial in question sound nothing like "kangaroo," which seems to have sprung into existence just about the time of Cook's explorations. However, slangmeister Eric Partridge declares that kangaroo is in fact of aboriginal origin and means "jumping quadruped." Someday we definitely have to get this straightened out.

Urban Legend has it that Kangaroo means "I Don't Know" in one of the local Aboriginal dialects to Sydney cove ... sadly, it's false, makes a nice story but...

http://www.thefreedictionary.com/kangaroo

"A common legend about the kangaroo's English name is that it came from the Aboriginal words for "I don't understand you." According to this legend, Captain James Cook and naturalist Sir Joseph Banks were exploring Australia when they happened upon the animal. They asked a nearby local what the creatures were called. The local responded "Kangaroo", meaning "I don't understand you", which Cook took to be the name of the creature."

https://en.wikipedia.org/wiki/Kangaroo

The kernel of truth underlying the story is that Captain James Cook, the first European explorer to reach Australia in 1770, did indeed bring back news of a creature the Australian native peoples called a "kangooroo" or "ganguru." Unfortunately, linguists cataloging the various Aboriginal languages many years later were unable to find anything like "kangaroo" in any existing native tongue. But the logical presumption is that the dialect Cook heard had simply become extinct over the intervening years. There is no evidence that "kangaroo" ever meant "I don't know," "What are you talking about," or any of the other responses supposedly given to his query.

http://www.word-detective.com/110999.html

This sounds believable to me.

kangaroo (n.)
1770, used by Capt. Cook and botanist Joseph Banks, supposedly an aborigine word from northeast Queensland, Australia, usually said to be unknown now in any native language. However, according to Australian linguist R.M.W. Dixon ("The Languages of Australia," Cambridge, 1980), the word probably is from Guugu Yimidhirr (Endeavour River-area Aborigine language) /gaNurru/ "large black kangaroo.

"In 1898 the pioneer ethnologist W.E. Roth wrote a letter to the Australasian pointing out that gang-oo-roo did mean 'kangaroo' in Guugu Yimidhirr, but this newspaper correspondence went unnoticed by lexicographers. Finally the observations of Cook and Roth were confirmed when in 1972 the anthropologist John Haviland began intensive study of Guugu Yimidhirr and again recorded /gaNurru/." [Dixon]

Kangaroo court is American English, first recorded 1850 in a Southwestern context (also mustang court), from notion of proceeding by leaps.

http://www.etymonline.com/index.php?term=kangaroo