[ sem-ee, sem-ahy ]
/ ˈsɛm i, ˈsɛm aɪ /
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See synonyms for: semi / semis on Thesaurus.com

noun Informal.



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“Was” is used for the indicative past tense of “to be,” and “were” is only used for the subjunctive past tense.

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Origin of semi

By shortening

Definition for semi (2 of 2)


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-

words often confused with semi-

See bi-1.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

Example sentences from the Web for semi

British Dictionary definitions for semi (1 of 2)

/ (ˈsɛmɪ) /

noun plural semis

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

British Dictionary definitions for semi (2 of 2)



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

Medical definitions for semi



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.

Scientific definitions for 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.