The word "superfluous" origninates from the Latin word "superfluus," meaning "overflowing" or "running over."  This Latin term itself is a combination of "super" (meaning "over" or "more") and "fluere" (meaning "to flow"). Therefore, etymologically, "superfluous" literally translates to "flowing over" or having more than is needed. 

According to the Oxford English Dictionary, the word "superfluous" was first used in English in the 15th century, before 1450.  The OED's earliest evidence for the word comes from the writings of John Arderne.

Examples of "superfluous" used in a sentence:  
"Why do we have superfluous, but potentially deadly vestiges like the appendix or wisdom teeth?" 
"Unnecessary, superfluous comments waste time and try the patience of participants."  
"To recount in detail their last night almost would be superfluous." 
"The drama of the race was almost superfluous."
"Of course we are all against unnecessary regulation and superfluous administrator.
"Thousands of hours of collective practice have rendered this skill superfluous."

Just the facts:

SUPERFLUOUS Definition & Meaning - Merriam-Webster

SUPERFLUOUS Synonyms: 41 Similar and Opposite Words | Merriam-Webster Thesaurus