What Are Some Two-Letter Prefixes?

What Are Some Two-Letter Prefixes?

Two-letter prefixes in the English language include "bi-," "co-," "de-," "re-" and "un-." Another two-letter prefix, "In," meaning "not," has the variants "il-," im-" and "ir-," based upon the letter at the beginning of the root word the prefix modifies. "Co-," meaning together, takes a third letter for similar variants.

The prefixes listed above can all be added to roots that can stand alone as common English words, for example, in "biweekly," "copilot," "devalue," "readmit" and "unfinished." However, prefixes also include elements that come at the beginning of words without roots that can stand alone. Examples include "ad-" in "adhere" and "ex-" in "exterior. Prefixes used with roots that are independent words sometimes take hyphens, but whether or not hyphens should be used in such words is often a matter of style, not strict rules of proper English usage.