Superfluous definition

so͝o-pûrflo͝o-əs

Being beyond what is required or sufficient.

adjective

Being more than is needed, useful, or wanted; surplus; excessive.

adjective

The definition of superfluous is something that is more than needed or unnecessary.

An example of superfluous is a buying a stuffed animal for a child who already has too many stuffed animals.

adjective

Not needed; unnecessary; irrelevant.

A superfluous remark.

adjective

In excess of what is required or sufficient.

With a full rain suit, carrying an umbrella may be superfluous.

adjective

(obs.) Extravagant; prodigal.

adjective

Origin of superfluous

Middle English from Old French superflueux from Latin superfluus from superfluere to overflow super- super- fluere to flow bhleu- in Indo-European roots

From American Heritage Dictionary of the English Language, 5th Edition
From Latin superfluus (“superfluous"), from superfluō (“overflow"), from super (“above,more than, over") + fluō (“flow"). Compare mellifluous and fluid, also from Latin. Literally corresponds to overflow, which is from Germanic, rather than Latin.

From Wiktionary