Go to 'thermo-' entry Go to 'dino-' entry Go to 'chondro-' entry Go to 'aero-' entry Go to '-logy' entry Go to 'thaumato-' entry Go to 'nano-' entry Go to '-sophy' entry Go to 'bucco-' entry Go to '-ism' entry Go to '-lysis' entry Go to 'galacto-' entry Go to '-anthropy' entry Go to 'pneumo-' entry Go to '-ploitation' entry Go to '-lithic' entry Go to '-sepalous' entry Go to 'onco-' entry Go to '-parous' entry Go to 'dermato-' entry Go to 'multi-' entry Go to 'dodeca-' entry Go to '-zoon' entry Go to 'vermi-' entry Go to 'crystallo-' entry Go to 'biblio-' entry Go to 'eco-' entry Go to 'juxta-' entry Go to 'facio-' entry
Affixes: the building blocks of English
Affixes: the building blocks of English

semi-

Half; a part.

[Latin semi-, half.]

The strict sense of a half occurs only in a minority of words, of which examples are semicircle; semidiameter; semilunar, shaped like a half-moon or crescent; and semiquaver, in British musical terminology a note having the time value of half a quaver, a sixteenth note. A few terms extend the idea to that of occurring twice in some time period, as in semi-annual, occurring twice a year (nominally every half year), and the North American semi-monthly, occurring or published twice a month (or every half month). A related idea occurs in semi-final, a match or round immediately preceding the final, the ‘half-final’.

Most terms in the prefix, however, signal that something is partially or incompletely so: semi-professional, semi-conscious, semi-retired, semi-literate, semi-skilled, semi-derelict, semiprecious, semiconducting (of a substance that has a conductivity between that of an insulator and that of most metals), and semipermeable (of a material or membrane that allows certain substances to pass through it but not others).

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