Merriam-Webster's Collegiate® Dictionary, 11th Edition
SEMI
I. noun (plural semis)
Etymology: short for semidetached
Date: 1912
a semidetached house,
II. noun (plural semis)
Date: 1942
semitrailer ,
III. noun (plural semis)
Date: 1942
semifinal
I. noun (plural semis)
Etymology: short for semidetached
Date: 1912
a semidetached house,
II. noun (plural semis)
Date: 1942
semitrailer ,
III. noun (plural semis)
Date: 1942
semifinal