sub Meaning, Definition & Usage

1. noun 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
   wedge; bomber; hero; hero sandwich; poor boy; submarine; zep; Cuban sandwich; grinder; torpedo; hoagie; Italian sandwich; hoagy; submarine sandwich.
   
2. noun a submersible warship usually armed with torpedoes
   submarine; U-boat; pigboat.
   
3. verb be a substitute
   fill in; stand in; substitute.
   
   • The young teacher had to substitute for the sick colleague
   • The skim milk substitutes for cream--we are on a strict diet

WordNet