Word of the Day : September 22, 2015


adjective BYE-nuh-ree


1 : consisting of two things or parts

2 : relating to, being, or belonging to a number system having 2 as its base

3 : involving a choice between or condition of two alternatives only (such as on-off or yes-no)

Did You Know?

As the old children's song goes, "The animals went in two by two, the elephant and the kangaroo…." It was a binary parade of sorts that went into Noah's ark "for to get out of the rain"—the critters were represented in pairs. If you recall those doubled up beasts, you'll remember the etymology of binary because it traces to the Latin bini, which translates as "two by two." Although binary can be used for anything with two parts, it is now used especially in relation to computers and information processing. Digital computers use the binary number system, which includes only the digits 0 and 1, to process even complex data. In binary form, for instance, the word HELLO looks like this: 01001000 01000101 01001100 01001100 01001111.


Brass is a binary alloy, having the two metallic elements copper and zinc.

"NASA's New Horizons is described as a mission to Pluto, but one of the reasons the dwarf planet is so fascinating to scientists is that it's part of the only known binary planet system in our solar system." — Karen Kaplan, The Los Angeles Times, 15 July 2015

Test Your Vocabulary

What 5-letter adjective begins with "d" and is used to describe a measure of music having two beats or a multiple of two beats?



More Words of the Day

Love words? Need even more definitions?

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