Substitute the mystery word for one that seems to make sense based on the context of the sentence or paragraph the word is in. For example, in the sentence "Lucy is extroverted and has many friends," if someone did not know what extroverted meant, she would probably be more likely to substitute it with something like "outgoing" rather than "shy" due to the context of "has many friends."
Continue reading the text with the substituted word in mind to verify that you interpreted the mystery word correctly. If you did not, go back to the mystery word and try another substitution.
Look for a definition or a synonym of the mystery word within the same sentence or within a surrounding sentence. A definition or explanation may be obvious if the mystery word is followed by words such as "means," "is," "refers to" or "is described as." Other clues that suggest the unknown word's definition are explanatory words in between parentheses or commas immediately next to the word. For example, "cyan" is defined: "cyan (a light blue)"; "Halifax" is explained: "Halifax, a Canadian city,..." Words such as "or" or "in other words" next to the unknown word may also be clues of a definition for that word.
Use antonyms as clues for determining the meaning of a new vocabulary word in certain cases. Antonyms are the opposite of synonyms. For example, a synonym for "wet" is "moist" and an antonym for "wet" is "dry." In this example sentence, if you do not know the meaning of "flippant," you can guess its meaning by its antonym "serious": "The brothers had different personalities; Andy was usually serious, whereas Joey was truly flippant."
Use examples, and words following terms like "such as," "for example," "for instance," and "i.e." to build your vocabulary with new words. For example, if you did not know the word "ornithologist," you could probably figure it out from the examples in this sentence: "The ornithologist studied various species, such as robins, blue jays, chickadees and sparrows."