n. a sandwich made from a long roll split lengthwise and filled with meat and cheese, as well as a combination of onions, peppers, tomatoes, pickles, or olives; "He ordered an Italian sandwich loaded with salami and provolone."

n. a submersible warship usually armed with torpedoes

v. be a substitute; "The young teacher had to substitute for the sick colleague"; "The skim milk substitutes for cream--we are on a strict diet"