Not every word in English needs to stand alone. Sometimes, words like to join up. And these compound words may have a completely new meaning. But how can you avoid errors when using these terms? Join us for a look at open, hyphenated, and closed compound words.\n\nWhat Are Compound Words?\nCompound words are made up of two or more other words. They can be written as open compounds, hyphenated compounds, or closed compounds:\n\n\n \tOpen compounds\u00a0are written as separate words, but they are conventionally used together (e.g.,\u00a0full moon,\u00a0mobile phone,\u00a0ice cream).\n \tHyphenated compounds\u00a0occur when two or more terms are joined with a hyphen (e.g.,\u00a0mother-in-law,\u00a0well-known,\u00a0T-shirt).\n \tClosed compounds\u00a0are written as a single term but combine two or more words that could be written separately (e.g.,\u00a0notebook,\u00a0boyfriend,\u00a0childlike).\n\nThe question is often what type of compound word you need to use!\n\nOpen, Hyphenated, or Closed?\nAs explained above, compound words come in three kinds. Which type of compound to use is often a matter of convention, so if you\u2019re not sure whether a word should be open, hyphenated, or closed, you can look it up in a reliable dictionary to see how they spell it.\n\n\n[caption id="attachment_4148" align="aligncenter" width="275"] Or ask the Spice Girls, who are experts on when two become one.(Photo: Ezekiel\/wikimedia)[\/caption]\nWith some words, though, you have more than one option. \u201cEmail,\u201d for example, can also be written as \u201ce-mail,\u201d and \u201ccar pool\u201d can be spelled \u201ccarpool.\u201d In these cases, our main tip is to use one spelling consistently throughout the document you\u2019re writing. And if you are using a style guide, you may want to check if it specifies how to write compound words.\nIn addition, we have a few tips for when to hyphenate compound words.\n\nWhen to Hyphenate Compound Words\nThe rules about\u00a0hyphenating\u00a0compound words are fairly flexible, but they can be useful. The most common guidelines are to hyphenate:\n\n\n \tWhen using a compound modifier before the word it modifies (e.g., a well-laid plan or a mind-numbingly boring speech).\n \tWhen writing compound numbers between twenty-one and ninety-nine.\n \tWith ages and time spans in years (e.g.,\u00a0a seven-year itch).\n\nHowever, you would not usually hyphenate compound adjectives when the first term is either \u201cvery\u201d or an adverb ending in \u201c-ly.\u201d For example:\nShe found a\u00a0perfectly formed\u00a0gemstone.\u00a0\u2713\nShe found a\u00a0perfectly-formed\u00a0gemstone.\u00a0\u2717\nNor would you usually hyphenate compound adjectives when they come after the noun they modify. For instance:\nThe plan was\u00a0well meaning.\u00a0\u2713\nThe plan\u00a0was\u00a0well-meaning.\u00a0\u2717\nAgain, there\u2019s some variation here (e.g., \u201cold-fashioned\u201d is almost always hyphenated, even when it appears after the term it modifies). But, as long as you\u2019re consistent and you remember to check a dictionary if you\u2019re unsure about a word, you should be able to avoid errors.\n\nOne Word or Two?\nCompound words often have meanings that differ from their constituent parts. This makes it easy to accidentally use a compound when you really need two separate words.\u00a0\u201cEveryday," for example, is an adjective meaning \u201cordinary\u201d or \u201croutine.\u201d It should be used like this:\nMy\u00a0everyday\u00a0clothes were in the wash, so I wore pajamas to the pub.\nThis isn\u2019t the same as \u201cevery day,\u201d which is written as two words and means \u201ceach day.\u201d As such, it\u2019s important not to get these terms confused if you want to be clear about what you mean. Remember:\nI go to the pub every day.\u00a0\u2713\nI go to the pub everyday.\u00a0\u2717\nSimilar terms include \u201calready\u201d and \u201caltogether,\u201d which have distinct meanings from \u201call ready\u201d and \u201call together.\u201d It\u2019s often worth thinking about whether you really need a compound word, or whether you really need two terms.\n\nNouns and Verb Phrases\nOne tip that can help is considering whether a compound word is being used as a noun or a verb phrase. Typically, the noun forms are written as a single closed compound. For instance, "set" and "up" become "setup":\nMy computer\u00a0setup\u00a0cost me thousands of dollars.\nHere, for example, \u201csetup\u201d is one word because it refers to a thing, not an action. The verb form of this term would be the two-word \u201cset up\u201d:\nIt took me hours to\u00a0set up\u00a0my computer.\nOther terms where these rules apply include \u201cworkout\u201d (verb = \u201cwork out\u201d), \u201cbackup\u201d (verb = \u201cback up\u201d) and \u201chandout\u201d (verb = \u201chand out\u201d).\nLook out for similar noun\u2013verb distinctions in your writing!\n\nIncorrect Compounds\nFinally, some terms are incorrectly written as compound words even when there\u2019s no correct version. Examples include \u201calot\u201d (which should be \u201ca lot\u201d) and \u201cnevermind\u201d (which should be \u201cnever mind,\u201d except the\u00a0Nirvana album).\n\n\n[caption id="attachment_3241" align="aligncenter" width="365"] For us, Kurt Cobain's musical legacy is outweighed by the number of spelling errors he's inspired.[\/caption]\nBut these are simply errors and should be avoided in your written work.\nIn other cases, it is less clear. The word \u201calright,\u201d for instance, is sometimes accepted as an alternative to saying \u201call right.\u201d But \u201calright\u201d is very informal. Some even consider it a spelling mistake. As such, you should be careful about using this compound word in formal writing.\nAnd if you\u2019re ever unsure about compounds, ask a proofreader for help!