sauceyoudaoicibaDictYouDict[sauce 词源字典]
sauce: [14] Sauce is one of a range of English words (others include salad, salary, and sausage) that go back ultimately to Latin sāl ‘salt’ (a relative of English salt). From it was formed the adjective salsus ‘salted’, whose feminine form salsa was used in Vulgar Latin for a ‘brine dressing or pickle’. This later evolved into Italian and Spanish salsa ‘sauce’ (the latter adopted into English as salsa [20]) and French sauce, from which English gets sauce.

The derivative saucy ‘cheeky’ no doubt arose from the ‘piquancy’ or ‘tartness’ of sauces. Saucer [14] originally meant ‘sauceboat’, and was borrowed from Old French saussier, a derivative of sauce. The modern application to a ‘dish for a cup’ did not evolve until the 18th century.
=> salt, saucer[sauce etymology, sauce origin, 英语词源]
sauce (n.)youdaoicibaDictYouDict
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 compare sass). Slang meaning "liquor" first attested 1940.
sauce (v.)youdaoicibaDictYouDict
mid-15c., "to season," from sauce (n.). From 1862 as "to speak impertinently." Related: Sauced; saucing.