Definition

/ɡɹeɪt/

noun

A person of major significance, accomplishment or acclaim.
“Newton and Einstein are two of the greats of the history of science.”
The main division in a pipe organ, usually the loudest division.
(in combinations such as "two-greats", "three-greats" etc.) An instance of the word "great" signifying an additional generation in phrases expressing family relationships.
“My three-greats grandmother.”

adjective

Relatively large in scale, size, extent, number (i.e. having many parts or members) or duration (i.e. relatively long); very big.
“A great storm is approaching our shores.”
Of larger size or more importance than others of its kind.
“the great auk”
(qualifying nouns of family relationship) Involving more generations than the qualified word implies — as many extra generations as repetitions of the word great (from 1510s). [see Derived terms]
“great-grandfather, great-great-grandfather, great-great-great-grandfather”

adverb

Very well (in a very satisfactory manner).
“Those mechanical colored pencils work great because they don't have to be sharpened.”

interjection

Expression of gladness and content about something.
“Great! Thanks for the wonderful work.”
Sarcastic inversion thereof.
“Oh, great! I just dumped all 500 sheets of the manuscript all over and now I have to put them back in order.”