Apart is defined as a whole thing being broken down into units.(adverb)
A very old building that is rotting with pieces falling off of it is an example of a building that is falling apart.
The definition of apart are things that are not together in any way, such as things separated by time or distance.(adverb)
A child born three years after his brother is an example of a child who is three years apart from his brother.
See apart in Webster's New World College Dictionary
Origin: ME < OFr a part < L ad, to, at + partem, acc. of pars, a side, part
See apart in American Heritage Dictionary 4
Origin: Middle English
Origin: , from Old French a part
Origin: : a, to (from Latin ad-; see ad-)
Origin: + part, side (from Latin pars, part-; see part).
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