semi

¹

[sem-ee, sem-ahy]

noun

Informal.

1. semitrailer.

2. Often semifinal.

semi-

²

1. a combining form borrowed from Latin, meaning “half,” freely prefixed to English words of any origin, now sometimes with the senses “partially,” “incompletely,” “somewhat”.

   semiautomatic; semidetached; semimonthly; semisophisticated.

semi

¹

/ ˈsɛmɪ /

noun

1. a semidetached house

2. short for semifinal

3. short for semitrailer

semi-

²

prefix

1. half Compare demi- hemi-

   semicircle

2. partially, partly, not completely, or almost

   semiprofessional

   semifinal

3. occurring twice in a specified period of time

   semiannual

   semiweekly

semi–

1. A prefix that means “half,” (as in semicircle, half a circle) or “partly, somewhat, less than fully,” (as in semiconscious, partly conscious).

Confusables Note

See bi- ¹.

Word History and Origins

Origin of semi–¹

By shortening

Origin of semi–²

Middle English < Latin sēmi-; cognate with Old English sōm-, sām- half (modern dial. sam- ), Old High German sāmi-, Sanskrit sāmi-, Greek hēmi-; sesqui-

Word History and Origins

Origin of semi–¹

from Latin; compare Old English sōm-, sām- half, Greek hēmi-

Example Sentences

Fortunately, his North Carolina home is the perfect locale for a “semi” retirement, providing a relaxing and calm sanctuary that was designed to optimize lake views from nearly every room.

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Home advantage for the final – which, like the semi, will be played over one leg – will be decided during the same draw.

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A BBC reporter on the scene said two police officers were guarding the door of a semi detached house behind a police cordon.

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Video from a dashboard camera from ABC7 showed the semi truck slamming into the car in front of it and plowing ahead through passenger cars, then finally slamming into a truck.

Read more on Los Angeles Times

A deal could also face challenges from U.S. regulators who “would also have to allow a Japan tech conglomerate to acquire one of the more valuable U.S. semi assets for AI/networking/optical,” Klein said.

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When To Use

What does semi- mean?

Semi- is a combining form used like a prefix meaning “half.” In some instances, it is used figuratively to mean "partially," "incompletely," or "somewhat." It is often used in a variety of technical and everyday terms.Semi- comes from Latin sēmi-, meaning “half.” The Greek cognate of sēmi- is hēmi-, also meaning “half,” which is the source of English terms such as hemialgia and hemicardia. To learn more, check out our entries for both words.