plural semis
: semifinal
often used in plural
plural semis
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

Examples of semi in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Noun
Lake County crash investigators determined that the semi was traveling south on U.S. 41 at the time of the crash. Post-Tribune, Chicago Tribune, 25 Feb. 2025 This semi represented her 200th career singles pro win on tour. Todd Boss, Forbes, 25 Feb. 2025 Nikola manufactured both hydrogen-electric and battery-electric semi trucks, and its fueling network has dispensed more than 330 metric tons of hydrogen, said Chief Executive Steve Girsky. Caroline Petrow-Cohen, Los Angeles Times, 19 Feb. 2025 The semi and Toyota collided, redirecting the Toyota into the center lane of I-70 where a Honda Accord struck it, according to court documents. Robert A. Cronkleton, Kansas City Star, 29 Jan. 2025 See All Example Sentences for semi

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

Browse Nearby Words

Cite this Entry

“Semi.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/semi. Accessed 24 Mar. 2025.

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
Etymology

Prefix

Latin semi- "half"

More from Merriam-Webster on semi

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