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?

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rudimentary British  

/ ˌruːdɪˈmɛntərɪ /

adjective

1. basic; fundamental; not elaborated or perfected

2. incompletely developed; vestigial

   rudimentary leaves

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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.

Example Sentences

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

Those early demonstrations were rudimentary, with the drones able to fly together at a set distance and little else.

From The Wall Street Journal • Jan. 25, 2026

Until high school, I didn’t speak a lick of any language other than English — save for some rudimentary Spanish counting and what little of Spanish and French that kids pick up through the media.

From Salon • Jan. 18, 2026

They’d spent long days slogging through the snow, freezing nights in whatever rudimentary shelter they could assemble or in the deserted huts of whaling camps when they were lucky enough to come across them.

From "Six of Crows" by Leigh Bardugo

Related Words

• elemental
• elementary
• embryonic
• primitive
• simple