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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

Related Words

See elementary.

Other Word Forms

  • nonrudimental adjective
  • nonrudimentarily adverb
  • nonrudimentarilyness noun
  • nonrudimentary adjective
  • rudimentarily adverb
  • rudimentariness noun

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.

Keep Reading on Vocabulary.com

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.

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

For now, though, Londoners are falling victim to more rudimentary scams at an alarming rate, Rory Innes, chief executive of The Cyber Helpline, said.

From BBC • Mar. 14, 2026

"It's the most rudimentary mine, the cheapest one, and the main threat in the Strait of Hormuz," said the former high-ranking member of the navy.

From Barron's • Mar. 11, 2026

While rudimentary, the Odyssey broke a barrier in the world of television.

From The Wall Street Journal • Jan. 22, 2026

Taisin had learned some rudimentary healing practices at the Academy, but she was not trained as a healer, and Kaede had never reached that far in her studies.

From "Huntress" by Malinda Lo