The method of preserving something, usually fish, by marinating it in a sauce with vinegar (plus perhaps oil, wine, onions, pepper, spices, etc) before or after frying. Common fish include anchovies and sardines, tuna and trout. In Puglia they usually add saffron and bread crumbs to the scapece, as in the famous scapece gallipolina, made usually with pesce azzurro.
Olives get the scapece treatment too, as well as vegetables: zucchine alla scapece, with mint and garlic, and sometimes carrots, is a popular Neapolitan dish.
Other spellings include scabecciu and scabéggio.