Meaning : A large sandwich made of a long crusty roll split lengthwise and filled with meats and cheese (and tomato and onion and lettuce and condiments). Different names are used in different sections of the United States.
Synonyms : bomber, cuban sandwich, grinder, hero, hero sandwich, hoagie, hoagy, italian sandwich, poor boy, submarine, submarine sandwich, torpedo, wedge, zep
Meaning : Be a substitute.
Example :
The young teacher had to substitute for the sick colleague.
The skim milk substitutes for cream--we are on a strict diet.
Synonyms : fill in, stand in, substitute