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semi-

pref.

1. Half: semicircle.

2. Partial; partially: semiconscious.

3. Resembling or having some of the characteristics of: semiofficial.

4. Occurring twice during: semimonthly. See Usage Note at bi-¹.

[Middle English, from Latin sēmi-, half; see sēmi- in the Appendix of Indo-European roots.]

sem·i

(sĕmī, sĕmē)

n. pl. sem·is
Informal

a. A semitrailer.

b. A tractor-trailer.

2. A semifinal.

3. A semiformal dance.

Indo-European & Semitic Roots Appendices

Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:

Indo-European Roots

Semitic Roots

The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.

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