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Bin– is a combining form used like a prefix, and it means “two” or “two at a time.” While it appears in a variety of scientific terms, it’s also easily recognizable in everyday terms.

Bin– comes from the Latin ��ī��ī, meaning “two each” or “by twos.”

Bin– is related to the combining form bi– and is used with some words or word elements beginning with vowels. These two forms have similar origins, and for that reason, the difference between the two is a small yet important nuance: bin– tends to mean “double,” while bi– often means “twice.” Want to know more? Read our 51�Թ�s That Use bi– article.

One example of a term that features the combining form bin– is binoculars, “an optical instrument for use with both eyes, consisting of two small telescopes joined together.”

The first portion of the word, bin-, means “two.” But what about the second half of the word? Ocular has various meanings, including “eyepiece,” a term for the lens or combination of lenses in an optical instrument. Binoculars literally translates to “two eyepieces.”

What are some words that use the combining form bin-?

• binary (using the equivalent form of bin– in Latin)
• binate (using from the equivalent form of bin– in Latin)
• binaural
• binotic
• binovular
• binoxalate

What are some other forms that bin– may be commonly confused with?

• bene-
• biblio-
• bio-
• bis-

Not every word that begins with the exact letters bin– uses the combining form bin– to denote “two.” Nouns such as bindle and bind appear on the surface to include bin-, but the similarity is a coincidence. Nor is bin– related to bin, as in a “box” or “container.” Learn the origins of these closely bound words at their respective entries.

The word aural means “of or relating to the ear.” With this in mind, what does binaural mean?