IPA: /ˈɡreɪtɪst/
KK: /ˈɡreɪtɪst/
The highest in quality or degree; the best or most important.
She is considered the greatest athlete of all time.
Greatest → It is formed from "great" (from Old English *grēat*, meaning large or big) and "-est" (a superlative suffix indicating the highest degree). The word "greatest" means the largest or most significant in comparison to others.
Think of something that is the 'largest' or 'most significant' — 'great' means large, and '-est' shows it is the highest degree.