The word "sustenance" comes from Middle English "sustenaunce," which derived from the Old French "sostenance" or "sustenance," meaning "support" or "aid".  The Old French word, in turn, comes from the Latin verb sustinere, meaning "to hold up" or "to endure". This Latin verb is formed from the prefix sub- ("up from below") and the verb tenere ("to hold"), ultimately stemming from the Proto-Indo-European root *ten-, meaning "to stretch". 

According to the Oxford English Dictionary (OED), the word "sustenance" was first used in English around 1300, during the Middle English period (1150-1500).  The OED cites a passage from a text about St. Francis as its earliest evidence. 

Examples of the word "sustenance" used in sentences: 
"People can and do draw sustenance from many sources."  
"The village depends on the sea for sustenance." 
"Tree bark provides deer with sustenance in periods of drought."  
"She draws spiritual sustenance from daily church attendance."  
"The birds get sustenance, and the berries get to disperse their seeds." 

10 minutes ago, drpaladin said:

I can hear W. C. Fields intoning his need for his favorite liquid sustenance.

Damn, you are really old!    

Just the facts:

SUSTENANCE Definition & Meaning - Merriam-Webster

SUSTENANCE Synonyms: 10 Similar and Opposite Words | Merriam-Webster Thesaurus