The definition of instantaneous is something that happens right away.(adjective)
If you ask for water and water immediately appears that very second, this is an example of something instantaneous.
See instantaneous in Webster's New World College Dictionary
Origin: ML instantaneus
See instantaneous in American Heritage Dictionary 4
Origin: From Medieval Latin īnstantāneus
Origin: , from Latin īnstāns, īnstant-, present; see instant.
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