1) moved by one's own impulse, or acting without the instigation or intervention of another
2) often used of the earth producing plants of itself, and of the plants themselves and the fruits growing without culture
Part of Speech: adjective
From G846 and the same as G3155; self moved ("automatic"), that is, spontaneous: - of own accord, of self.
|without any cause||89.21|
These two sites give similar information, with the definition from several dictionaries and statistics on the use of the word.
Perseus Digital Library
University of Chicago's Logion lexicon
Thayer's dictionary plus other information.
From this site's dictionary (in Italian)
Click on the first column to search for that word as a form of the root αὐτόματος; click on the second column to search for that grammatical form of the root αὐτόματος; click on the third column to search for that word and grammatical form; click on the total to search for the root αὐτόματος.