When you describe something as main, you mean it's the most important, well-known, or biggest of its kind. The main branch of the post office in a city is usually the largest and busiest.

The main theme of your English paper is your thesis, the basic, fundamental thing you're trying to express in your writing. The main road in town is the most busy and populated — in fact, in many places this road is called "Main Street." This adjective describes things that stand out as the most important or prominent in their category. In the thirteenth century, it meant "large or strong," and came from the Old English mægen, "power, strength, or force."

Definitions of main
  1. adjective
    most important element
    “the main doors were of solid glass”
    synonyms: chief, master, primary, principal
    important, of import
    of great significance or value
  2. adjective
    (of a clause) capable of standing syntactically alone as a complete sentence
    synonyms: independent
    see moresee less
    dependent, subordinate
    (of a clause) unable to stand alone syntactically as a complete sentence
  3. adjective
    of force; of the greatest possible intensity
    “by main strength”
    possessing or displaying a distinctive feature to a heightened degree
  4. noun
    a principal pipe in a system that distributes water or gas or electricity or that collects sewage
    see moresee less
    show 4 types...
    hide 4 types...
    electric main
    a main that distributes electricity
    gas main
    a main that distributes gas
    sewer line, sewer main
    a main in a sewage system
    water main
    main (a pipe or conduit) for conveying water
    type of:
    pipage, pipe, piping
    a long tube made of metal or plastic that is used to carry water or oil or gas etc.
  5. noun
    any very large body of (salt) water
    synonyms: briny
    see moresee less
    type of:
    body of water, water
    the part of the earth's surface covered with water (such as a river or lake or ocean)
Word Family

Test prep from the experts

Boost your test score with programs developed by’s experts.

  • Proven methods: Learn faster, remember longer with our scientific approach.
  • Personalized plan: We customize your experience to maximize your learning.
  • Strategic studying: Focus on the words that are most crucial for success.


  • Number of words: 500+
  • Duration: 8 weeks or less
  • Time: 1 hour / week


  • Number of words: 500+
  • Duration: 10 weeks or less
  • Time: 1 hour / week