(noun)
a style of jazz singing characterized by improvisation and the use of nonsensical syllables, often imitating the sound of an instrument;
e.g. She gave an excellent scat performance, accompanied by a jazz band.
(verb)
to engage in a particular style of jazz singing, characterized by improvisation and the use of nonsensical syllables, intended to imitate the sound of a musical instrument;
e.g. He started to scat, and the audience cheered.
(noun)
the droppings of an animal, especially a carnivorous animal;
e.g. If you see fresh tiger scat, you know that a tiger has been there recently.