Prefixes (such as "de-", "pre-", "re-", and "non-") and suffixes (such as ', ', ', and ') are sometimes hyphenated, especially when the unhyphenated spelling resembles another word or when the affixation is deemed misinterpretable, ambiguous, or somehow "odd-looking" (for example, having two consecutive monographs that look like the digraphs of English, like e+a, e+e, or e+i). However, the unhyphenated style, which is also called "closed up" or "solid", is usually preferred, particularly when the derivative has been relatively familiarized or popularized through extensive use in various contexts. As a rule of thumb, affixes are not hyphenated unless the lack of a hyphen would hurt clarity.