semi

¹

[ sem-ee, sem-ahy ]

noun

, Informal.

1. semitrailer ( def 1 ).
2. Often semifinal ( def 3 ).

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

   semifinal

   semiprofessional

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 semi¹

By shortening

Origin of semi²

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 semi¹

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

Example Sentences

He “did not adopt a reflexive posture to protect himself and ... he may have fallen in a state of semi- or total unconsciousness,” officials said.

From Los Angeles Times

To great fanfare, Musk introduced the Tesla Semi all-electric big rig in 2017.

From Los Angeles Times

It would hurt major truck makers and could destroy electric truck startup companies, while giving the long-delayed Tesla Semi time to catch up.

From Los Angeles Times

Fiji fly-half Caleb Muntz scored 19 points as the visitors sealed a first win in Wales, despite wing Semi Radradra receiving a first-half 20-minute red card for a dangerous tackle on full-back Cameron Winnett.

From BBC

He “did not adopt a reflexive posture to protect himself and ... he may have fallen in a state of semi- or total unconsciousness,” officials said last month.

From Los Angeles Times

Related Words

• car
• crate
• freighter
• jeep
• lorry
• pickup
• rig
• van
• wagon

Words That Use semi-

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.

Examples of semi-

An example of a word you may have encountered that features semi– is semicolon, “the punctuation mark (;).”

We know semi– means “half,” and a colon is the sign (:). The word colon itself comes from Greek kôlon, meaning “limb; part of a clause or period.” Semicolon literally translates to “half colon.”

What are some words that use the combining form semi-?

• semiannual
• semiautomatic
• semicircle
• semifinal
• semiliterate
• semiprivate

What are some other forms that semi– may be commonly confused with?

• semei-
• septi-

Break it down!

The word literate means “able to read and write.” With this in mind, what does semiliterate mean?