sub

nouns

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

Cuban sandwich, Italian sandwich, bomber, grinder, hero, hero sandwich, hoagie, hoagy, poor boy, sub, submarine, submarine sandwich, torpedo, wedge, zep

a submersible warship usually armed with torpedoes

U-boat, pigboat, sub, submarine

verbs

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"

fill in, stand in, sub, substitute

is derived from

subbing