semi

1 of 4

noun (1)

ˈse-ˌmī How to pronounce semi (audio)
also
-mē How to pronounce semi (audio)
plural semis
: semifinal
—often used in plural

semi

2 of 4

noun (2)

ˈse-ˌmī How to pronounce semi (audio)
also
-mē How to pronounce semi (audio)
plural semis
: semitrailer

semi

3 of 4

noun (3)

ˈse-mē How to pronounce semi (audio)
also
-ˌmī How to pronounce semi (audio)
plural semis
chiefly British
: a semidetached house

semi-

4 of 4

prefix

ˌse-mē,
-ˌmī,
-mi
1
a
: precisely half of:
(1)
: forming a bisection of
semidiameter
(2)
: being a usually vertically bisected form of (a specified architectural feature)
semidome
b
: half in quantity or value : half of or occurring halfway through a specified period of time
semiannual
semimonthly
compare bi-
2
: to some extent : partly : incompletely
semicivilized
semi-independent
semidry
compare demi-, hemi-
3
a
: partial : incomplete
semiconsciousness
semidarkness
b
: having some of the characteristics of
semiporcelain
c
: quasi-
semigovernmental
semimonastic

Word History

Etymology

Noun (3)

short for semidetached

Prefix

Middle English, from Latin; akin to Old High German sāmi- half, Greek hēmi-

First Known Use

Noun (1)

1942, in the meaning defined above

Noun (2)

1942, in the meaning defined above

Noun (3)

1912, in the meaning defined above

Time Traveler
The first known use of semi was in 1912

Phrases Containing semi

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Dictionary Entries Near semi

Semey

semi

semi-

See More Nearby Entries 

Cite this Entry

“Semi.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/semi. Accessed 7 Dec. 2022.

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Kids Definition

semi-

prefix
ˌsem-i,
ˈsem-,
-ˌī
1
: half in amount or value
semitone
2
: occurring halfway through a certain time period
semiannual
3
: to some extent : partly : incompletely
semitropical
4
: partial : incomplete
semidarkness

More from Merriam-Webster on semi

Thesaurus: All synonyms and antonyms for semi

Nglish: Translation of semi for Spanish Speakers

Britannica English: Translation of semi for Arabic Speakers

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