We like to think we're different from animals, but here's a hint: we're really not. Of all the laundry list of accomplishments and characteristics that we think make us different from the immense number of other creatures in the world, there are only a handful that they don't do too. Apart from the written word, there's almost nothing we do that other animals don't.
For it to be murder, it has to be within the species â€” in which case you can definitely call what some animals do as murder. They deliberately kill off members of their own species for non-survival reasons. One of the best documented cases of this is when a new alpha lion takes over a pride, all the cubs are slaughtered â€” like the Lion King, but less singing and dancing, and more wholesale infanticide. Chimpanzees too will gang up and kill individuals of the same or different species â€” and those guys are strong as all hell and prone to rage.