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
source: WordNet 3.0
a submersible warship usually armed with torpedoes
source: WordNet 3.0
A subordinate; a subaltern.
source: Webster 1913
verb
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.