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rudimentary

American  
[roo-duh-men-tuh-ree, -tree] / ˌru dəˈmɛn tə ri, -tri /
Often rudimental

adjective

  1. pertaining to rudiments or first principles; elementary.

    a rudimentary knowledge of geometry.

    Synonyms:
    initial, fundamental
    Antonyms:
    advanced
  2. Biology. of the nature of a rudiment; undeveloped or vestigial.

    Synonyms:
    embryonic
    Antonyms:
    mature
  3. in an early, imperfect stage or form.

    How can we improve upon this admittedly rudimentary theory?


rudimentary British  
/ ˌruːdɪˈmɛntərɪ /

adjective

  1. basic; fundamental; not elaborated or perfected

  2. incompletely developed; vestigial

    rudimentary leaves

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Synonym Usage

See elementary.

Other Word Forms

Derived Forms

Etymology

Origin of rudimentary

First recorded in 1600–20; rudiment + -ary

Explanation

Rudimentary means basic, or at a very early stage. The test should be easy: it requires only a rudimentary understanding of the materials. The word rude means simple or offensive — and people with only rudimentary understanding of good manners might not know how that belching is rude. If you remember that the word rude is the foundation of rudimentary, you'll have a rudimentary understanding of the word.

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Vocabulary lists containing rudimentary

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

“I went to see how these little stores in New York got their supplies, and I really thought it was very rudimentary and not very efficient,” he said during the talk in 2011.

From The Wall Street Journal • Mar. 30, 2026

The other was being recruited by Arnold Beckman, a Caltech alum, a renowned inventor of scientific instruments, and scientific advisor to L.A.’s rudimentary air pollution control operation.

From Los Angeles Times • Mar. 26, 2026

Anyone with even rudimentary knowledge of recent history would have known this was likely.

From Salon • Mar. 15, 2026

As it struck the ground, Istanbul Yurdum Spor's captain raced over and started performing rudimentary CPR, pumping its ribcage, according to footage sent to AFP by team manager Fatih Buyuk.

From Barron's • Feb. 24, 2026

Beyond these rudimentary details, nothing was known about the structure or function of DNA and RNA.

From "The Gene" by Siddhartha Mukherjee

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