/ ˌmeɪəˈneɪz; NAmE ˈmeɪəneɪz/ (also informal mayo / ˈmeɪəʊ; NAmE ˈmeɪoʊ/) noun
[ U ] a thick cold white sauce made from eggs, oil and vinegar , used to add flavour to sandwiches , salads, etc. :
egg mayonnaise (= a dish made with hard-boiled eggs and mayonnaise )
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WORD ORIGIN
French , probably from the feminine of mahonnais of or from Port Mahon , the capital of Minorca.