Is it ensure, insure, or assure?
mid-14c., from Old French sauce, sausse, from Latin salsa "things salted, salt food," noun use of fem. singular or neuter plural of adjective salsus "salted," from past participle of Old Latin sallere "to salt," from sal (genitive salis) "salt" (see salt (n.)).
Meaning "something which adds piquancy to words or actions" is recorded from c.1500; sense of "impertinence" first recorded 1835 (see saucy, and cf. sass). Slang meaning "liquor" first attested 1940.
mid-15c., "to season," from sauce (n.). From 1862 as "to speak impertinently." Related: Sauced; saucing.
liquid or semiliquid mixture that is added to a food as it cooks or that is served with it. Sauces provide flavour, moisture, and a contrast in texture and colour. They may also serve as a medium in which food is contained, for example, the veloute sauce of creamed chicken. Seasoning liquids (soy sauce, hot pepper sauce, fish sauce, Worcestershire sauce) are used both as ingredients in cooking and at table as condiments.