Learn English – the origin of the counting prefixes: uni-, bi-/di-, tri-, quad-, etc.


Many English words use the prefixes uni-, bi-/di-, tri-, quad- and so on to mean one, two, three, and four. For example:

A unicycle has one wheel, a bicycle two, and a tricycle three.

I presume these prefixes are either of Greek or Latin origin, but from what little I know of these two languages, neither uses these prefixes as their numbers. That is, in Greek you wouldn't start counting by saying, Uni, di, tri, quad, …

Best Answer

You are correct, they are from Latin and Greek, we have simply inherited terms from both. There is a good reference for Latin and Greek roots over at Wikipedia:

Uni meaning one:

un-, uni- one

  • language of origin: Latin

  • etymology: unus, unius

  • examples: unary, union

Bi/Di meaning two:

bi- two

  • language of origin: Latin

  • etymology: bis, "twice"; bini, "in twos"

  • examples: binoculars, bigamy, biscotti

di- two

  • language of origin: Greek

  • etymology: δι,

  • examples: dicot, dipole

Quadr meaning four:

quadr- four

  • language of origin: Latin

  • etymology: quattuor

  • examples: quadrangle, quadrillion

And so on; there are a lot of these and I'm no expert but believe that, although some of the roots from Latin and Greek essentially mean the same, there are some constraints on which ones to use in certain circumstances (see also: hypercorrection.) But don't quote me on that, though, I'll try and look a little information up.