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semi

[sem-ee, sem-ahy]
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SEE MORE SYNONYMS FOR semi ON THESAURUS.COM

noun Informal.

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

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Does bimonthly mean twice a month or every two months?
The prefix bi- usually means ‘every two’, so bimonthly means ‘every two months’.Semi- means ‘half’ or ‘halfway’, so semimonthly means ‘every two weeks’. However, bimonthly can also mean ‘twice a month’ – but it is rarely used that way. It is best to remember that bi- is “every two” and semi- is “halfway.”
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GEOTUS
Read more in this article about some frequently asked questions and fun facts related to our definitions.
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RELATED WORDS

wagon, van, car, crate, pickup, rig, jeep, freighter, lorry, buggy, dump, wheels, carryall, apparent, apparently, fake, mock, near, nominal, partly

Origin of semi

by shortening

semi-

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.

Origin of semi-

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

Usage note

See bi-1.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for semi

Contemporary Examples of semi

Historical Examples of semi

  • Clearly these should only be planted in wild and semi–wild places.

    The Wild Garden

    William Robinson

  • Semi has had more success than I require, and considerably more than I expected.

  • Semi can give him the former, and over the latter our future journey lies.

    Buffalo Land

    W. E. Webb

  • Raising his hand in a semi salute, the man started into the woods.

  • It continues to be the resort of persons of every civilized, and almost every semi civilized, nation on the face of the earth.

British Dictionary definitions for semi

semi

noun plural semis

British a semidetached house
short for semifinal
US, Canadian, Australian and NZ short for semitrailer

semi-

prefix

halfsemicircle Compare demi- (def. 1), hemi-
partially, partly, not completely, or almostsemiprofessional; semifinal
occurring twice in a specified period of timesemiannual; semiweekly

Word Origin for semi-

from Latin; compare Old English sōm-, sām- half, Greek hēmi-
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Word Origin and History for semi

semi-

before vowels sem-, word-forming element meaning "half, part, partly; partial, imperfect; twice," from Latin semi- "half," from PIE *semi- "half" (cf. Sanskrit sami "half," Greek hemi- "half," Old English sam-, Gothic sami- "half").

Old English cognate sam- was used in such compounds as samhal "poor health," literally "half-whole;" samsoden "half-cooked," figuratively "stupid" (cf. half-baked); samcucu "half-dead," literally "half-alive;" and the last survivor of the group, sandblind "dim-sighted" (q.v.). Common in Latin (e.g. semi-gravis "half-drunk," semi-hora "half hour," semi-mortuus "half-dead," semi-nudus "half-naked," semi-vir "half-man, hermaphrodite"). The Latin-derived form in English has been active in forming native words since 15c.

Online Etymology Dictionary, © 2010 Douglas Harper
Medicine definitions for semi

semi-

pref.

Half:semicanal.
Partial; partially:semiconscious.
Resembling or having some of the characteristics of:semilunar.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Science definitions for semi

semi-

A prefix that means “half,” (as in semicircle, half a circle) or “partly, somewhat, less than fully,” (as in semiconscious, partly conscious).
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.