Meaning of 'sub'

noun

a submersible warship usually armed with torpedoes

Synonyms: submarine

noun

a large sandwich made of a long crusty roll split lengthwise and filled often filled with a combination of meats, cheese, tomato, onion, lettuce, and condiments

Example: "The local grocery store had the best subs where I grew up."

Synonyms: torpedo

verb

be a substitute

Example: "The young teacher had to substitute for the sick colleague"

Synonyms: substitute