Number Prefixes from Latin and Greek

Read number prefixes such as uni-, mono-, bi-, di-, tri-, cent-, and kilo- in words.

English borrows number words from both Latin and Greek, so you often get two prefixes for the same number. For one, Latin gives uni- (unicycle, uniform, unique) and Greek gives mono- (monologue, monorail). For two, Latin gives bi- (bicycle, bilingual) and Greek gives di- (dioxide, dilemma, a choice between two). Tri- means three in both languages (triangle, tripod, trilogy). Latin cent- means hundred (century, centimeter, percent) and Greek kilo- means thousand (kilogram, kilometer).

Spotting these makes math and science words easier. Take 'carbon dioxide': di- tells you there are two oxygen atoms. 'Bilingual' tells you two languages; 'monolingual' tells you one. A warning: 'decimal' and 'decade' come from Latin and Greek words for ten, but 'December' is the twelfth month because the old Roman calendar started in March, so it was once the tenth.

• 1One: uni- (Latin), mono- (Greek).
• 2Two: bi- (Latin), di- (Greek). Three: tri- in both.
• 3Hundred: cent-. Thousand: kilo-.