triangular number

noun

Definition of triangular number

: a number (such as 3, 6, 10, 15) representable by that many dots arranged in rows that form a triangle and that equals {latex}\frac{n(n + 1)}{2}{/latex} for some positive integer value of n

First Known Use of triangular number

1795


Learn More about triangular number


Seen and Heard

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

Love words? Need even more definitions?

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

WORD OF THE DAY

to speak or write verbosely and windily

Get Word of the Day daily email!

Test Your Vocabulary

Odd Habits and Quirks Quiz

  • image1926873504
  • Which of the following best describes an easily irritated person?
Spell It

Can you spell these 10 commonly misspelled words?

TAKE THE QUIZ
Dictionary Devil

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

TAKE THE QUIZ

Love words? Need even more definitions?

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