sub

If a history buff mentions a sub, she's probably referring to an underwater warship. But if your friend wants a sub for lunch, he hasn't suddenly developed a taste for warships — he just wants a sandwich.

Sub is short for submarine, the cylindrical watercraft with rounded ends that can operate deep beneath the water. Sub can also refer to a long sandwich filled with meat, cheese, and veggies; this kind of sub goes by different names in different parts of the country, including hero, hoagie, and grinder. The sub in your geometry classroom is probably just a substitute teacher.

Definitions of sub
  1. noun
    a submersible warship usually armed with torpedoes
    synonyms: U-boat, pigboat, submarine
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    types:
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    attack submarine
    a military submarine designed and armed to attack enemy shipping
    auxiliary research submarine
    a submarine for research purposes
    fleet ballistic missile submarine
    a submarine carrying ballistic missiles
    nautilus, nuclear submarine, nuclear-powered submarine
    a submarine that is propelled by nuclear power
    type of:
    submersible, submersible warship
    a warship designed to operate under water
  2. 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
    synonyms: Cuban sandwich, Italian sandwich, bomber, grinder, hero, hero sandwich, hoagie, hoagy, poor boy, submarine, submarine sandwich, torpedo, wedge, zep
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    type of:
    sandwich
    two (or more) slices of bread with a filling between them
  3. verb
    be a substitute
    synonyms: fill in, stand in, substitute
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    type of:
    change, exchange, interchange
    give to, and receive from, one another
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