Dictionary.com Word FAQs
How can I figure out if something should be one word or two, like anytime or any time?
You should choose one dictionary as your general guide for all of your writing so your hyphenation is consistent. To find out if something should be one word or two - look it up. Remember that there may be variants and the first form offered will be "preferred," but other variants listed are also acceptable. This is one of the stickier problems that copy editors worry about - whether a two-word phrase is two separate words, hyphenated, or combined to become one word. Concepts may start out as two words (e.g., common sense), become hyphenated as adjectives, and then eventually become one word (commonsense) as the usage becomes more commonplace. Many words and phrases tend to evolve from separation to linkage. The trend in English is for frequently used word combinations to "grow together" from two words to one, sometimes passing through a hyphenated stage. The two-word phrase "data base," for example, is now most commonly written as one word: "database." So, though the best rule is to check your chosen dictionary, there are a few principles that can be helpful. Two or more adjectives before a noun that act as one idea (one-thought adjectives) are connected with a hyphen. Example: He has a devil-may-care attitude. Use a hyphen in expressions where words have become linked by usage to express one idea, e.g., mother-in-law. Do not use a hyphen after an adverb ending with -ly, e.g., carefully planned project. Do not use a hyphen in a compound using a comparative or superlative adjective, e.g., the best laid plans. Do not use a hyphen in chemical terms, e.g., hydrogen peroxide solution. Do not use a hyphen in a modifier using a letter or numeral as the second element, e.g., Type A personality. When written as words, fractions and cardinal numbers consisting of two words are hyphenated, e.g., two-thirds. Hyphenate words prefixed by ex-, self-, or all-, and some words prefixed by cross-. Do not hyphenate words prefixed by non-, un-, in-, dis-, co-, anti-, hyper-, pre-, re-, post-, out-, b-i, counter-, de-, semi-, mis-, mega-, micro-, inter-, over-, and under- (among others) - unless the second element is capitalized. (But some are hyphenated when the second element starts with the letter ending the first element: pre-empt.) Do not hyphenate most verb and preposition combinations, e.g., the verb check out. Use hyphens when needed for clarity, e.g., dirty-picture magazine.