What does semi- mean

Semi is a prefix that often means half or partly. Its exact contribution depends on the word it forms. A semicircle is half a circle, while semiconscious describes a partial state rather than a precise numerical half.

Meaning and context

Do not assume that every semi word can be interpreted by inserting exactly fifty percent. Established usage determines the meaning of the complete word. A technical term may also have a definition specific to its field.

Examples and usage

Semiannual generally means occurring twice a year, while a semifinal is a round before a final. These examples show different established applications of the prefix. If a schedule affects a payment or appointment, confirm the actual dates rather than relying only on the prefix.

What to check

Hyphenation depends on the word and the editorial convention. Look up an unfamiliar compound rather than adding or removing a hyphen mechanically. Keep semi distinct from terms such as bi, which can create a different kind of ambiguity in timing expressions.

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