submarine

submarine — noun

1. A long, narrow military vessel built to navigate and carry out operations beneat

1.nounB2
Definition

A long, narrow military vessel built to navigate and carry out operations beneath the ocean surface, typically armed with torpedoes or guided missiles.

Example

Sade toured a retired Cold War submarine at the naval museum in Helsinki.

collocation: nuclear submarine / Cold War submarine

The submarine's sonar detected an unidentified vessel approaching from the east.

possessive: submarine's + equipment (sonar)

Common collocations
  • nuclear submarine
  • submarine commander
  • submarine crew
  • submarine patrol
  • submarine fleet
  • submarine base
Synonyms
  • sub

    informal short form, very common in spoken English and naval slang

  • U-boat

    specifically refers to German submarines of WWI and WWII, not used for modern vessels

  • submersible

    a smaller underwater vehicle that usually needs a support ship; different from a military submarine

Antonyms
  • surface ship

    any vessel that travels on top of the water rather than beneath it

Usage Note

This is the core sense and the most common use of the word. It always refers to a crewed military vessel — uncrewed underwater vehicles are called 'remotely operated vehicles' (ROVs) or 'autonomous underwater vehicles' (AUVs), not submarines.

Common Mistakes

The research team used a submarine to explore the deep sea.
The research team used a submersible to explore the deep sea.
Most scientific underwater vehicles are submersibles, not submarines, which are military vessels.

2. A filling sandwich built from a bread roll split down the middle and stacked wit

2.nounB1
Definition

A filling sandwich built from a bread roll split down the middle and stacked with cold cuts, cheese, fresh vegetables, and dressing.

Example

Christopher ordered a submarine with roast beef, cheddar, and spicy mustard.

submarine + with + [ingredients]

For the road trip, Lisa packed two foot-long submarines and wrapped them in wax paper.

quantifier: foot-long submarine

Common collocations
  • foot-long submarine
  • submarine sandwich
  • order a submarine
  • toast a submarine
Synonyms
  • sub

    the most common short form, understood across the US and increasingly in other English-speaking countries

  • hoagie

    the standard term in the Philadelphia region

  • hero

    the common name in the New York City area

  • grinder

    used especially in New England, often with toasted bread

Usage Note

This word is used in the northeastern United States. The same sandwich has many regional names — 'hero' (New York), 'hoagie' (Philadelphia), 'grinder' (New England), 'torpedo' (parts of the Midwest and West Coast). In other English-speaking countries, 'submarine sandwich' or just 'sub' is the most widely understood term.

Common Mistakes

I ate a submarine for breakfast.' (fine in American English but may confuse UK listeners)
I ate a sub for breakfast.
In British English, 'sub' is more common; 'submarine' for a sandwich is rarely used.

submarine — adjective

submarine — verb

Word family

Synonym discussion

Sense: noun/1

While submarine, submersible, sub, and U-boat all refer to underwater vessels, they mark important differences in function and context. A submarine is primarily a military vessel that can operate independently underwater for extended periods — it generates its own power and carries weapons. A submersible, by contrast, is much smaller, depends on a support ship for launch and recovery, and has limited range; it is used mainly for ocean research, underwater inspection, or tourism. Sub is the informal clipped form of submarine — common in casual speech ('Let's take a sub to the sandwich shop' is ambiguous, but 'The navy launched a sub' is clear). U-boat is a historical term for German submarines used during the world wars, from the German Unterseeboot meaning 'undersea boat'. In practice: 'The navy dispatched a nuclear submarine to patrol the Atlantic' suggests a long-range military mission, while 'The scientists descended in a submersible to study deep-sea vents' describes a tethered research dive.

submersible ↗sub ↗U-boat

Common collocations

Nouns

Adverbs

Phrases

  • nuclear submarine
  • submarine patrol
  • submarine fleet
  • submarine sandwich
  • submarine cable

Prepositions

Etymology

LatinFrenchEnglish

From the Latin prefix 'sub-' meaning 'under, below' combined with 'marinus' meaning 'of the sea' (from 'mare' — sea). The word first appeared in English during the mid-1600s as an adjective describing things located beneath the sea. Its use as a noun for an underwater vessel did not become common until the early 1900s, when the first practical military submarines entered service. The sandwich sense emerged in American English in the mid-1900s, named for the bread roll's resemblance to the vessel's long cylindrical shape.