nin·ja | \ˈnin-jə, -(ˌ)jä\
plural ninja also ninjas

Definition of ninja 

: a person trained in ancient Japanese martial arts and employed especially for espionage and assassinations

Keep scrolling for more

Did You Know?

Ninjas may seem mysterious, but the origin of their name is not. The word ninja derives from the Japanese characters "nin" and "ja." "Nin" initially meant "persevere," but over time it developed the extended meanings "conceal" and "move stealthily." In Japanese, "ja" is the combining form of sha, meaning "person." Ninjas originated in the mountains of Japan over 800 years ago as practitioners of ninjutsu, a martial art sometimes called "the art of stealth" or "the art of invisibility." They often served as military spies and were trained in disguise, concealment, geography, meteorology, medicine, and also other martial arts. Popular legends still associate them with espionage and assassinations, but modern ninjas are most likely to study ninjutsu to improve their physical fitness and self-defense skills.

Examples of ninja in a Sentence

Recent Examples on the Web

Unusual or replica weapons Don’t pack metal ninja stars or ornamental knives with blades hidden in canes or hair brush handles; people have tried to bring such items but the TSA always finds them — and dumps them. Fox News, "6 things to know the next time you go through airport security," 16 May 2018 For going on two decades now, the collaborative line between Adidas and Japanese flex god Yohji Yamamoto has artfully and innovatively explored the boundaries where high-performance athletic function meets high-fashion streetwear-ninja form. Yang-yi Goh, GQ, "The Best Backpacks for Work Will Make You Feel Like a Boss," 14 June 2018 The player advances to higher ninja levels by holding poses for longer periods of time. Sarah Deweerdt, Science | AAAS, "Can science-based video games help kids with autism?," 22 June 2018 The store is a dark forest of crepe dangling down from the ceiling into a crush of dinosaur piñatas and ninja piñatas and seven-pointed stars that look like Sputniks. Christopher Borrelli,, "Trump piñatas a hit across cultures," 16 May 2018 But its eerie grin isn’t even the most unique feature of this deep sea ninja. Katherine J. Wu, Smithsonian, "Why Bioluminescence Evolved to Be Red Light, and Blue," 26 June 2018 Her Catholic ninja origin story Like a lot of comic book characters who debuted in the ‘90s, Domino is a perfect mix of a simple, high concept layered with a ludicrously complicated backstory. Chris Sims, The Verge, "Domino deserves a spinoff film, and there are amazing comic stories to mine," 24 May 2018 Kyler loves anything to do with superheroes and will eagerly show you his 'ninja moves' upon request. Boys & Girls Aid / Community Content Partner,, "A Home of His Own: Kameron, 14, is both thoughtful and articulate.," 23 Mar. 2018 Indoor Activities: Uptown Jungle Fun Park Rock climbing, trampolines, ball-blaster arenas, super slides and ninja courses will entertain kids for hours at this entertainment center near Higley and Recker roads in Mesa. Wendy Killeen, azcentral, "Indoor playgrounds, trampoline parks and places in Phoenix kids can play and stay cool," 24 May 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'ninja.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of ninja

1964, in the meaning defined above

History and Etymology for ninja

Japanese, from nin- persevere, conceal, move stealthily + -ja person

Keep scrolling for more

Learn More about ninja

Listen to Our Podcast about ninja

Statistics for ninja

Last Updated

7 Sep 2018

Look-up Popularity

Time Traveler for ninja

The first known use of ninja was in 1964

See more words from the same year

Keep scrolling for more

More Definitions for ninja



English Language Learners Definition of ninja

: a fighter who is trained in the Japanese martial arts


nin·ja | \ˈnin-jə \
plural ninja also ninjas

Kids Definition of ninja

: a person trained in ancient Japanese martial arts who works as a spy and assassin especially in the past

Comments on ninja

What made you want to look up ninja? Please tell us where you read or heard it (including the quote, if possible).


to reject or criticize sharply

Get Word of the Day daily email!

Test Your Vocabulary

Words from Greek and Roman Mythology Quiz

  • the-triumph-of-venus-by-alessandro-magnasco
  • Boreal comes from the name of the ancient Greek god of which wind?
True or False

Test your knowledge - and maybe learn something along the way.

Word Winder's CrossWinder

Test Your Knowledge - and learn some interesting things along the way.


Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!