si

Multiple Entries:
  si    SI    Si    silicon  

Concise Oxford English Dictionary © 2008 Oxford University Press:
si /siː/

▶noun Music another term for te.

– origin C18: from the initial letters of Sancte Iohannes, the closing words of a Latin hymn.

Concise Oxford English Dictionary © 2008 Oxford University Press:
SI/esˈʌɪ/

▶abbreviation

• 1 Système International, the international system of units of measurement based on the metre, kilogram, second, ampere, kelvin, candela, and mole, together with prefixes indicating multiplication or division by powers of ten.

• 2 Law statutory instrument.

Concise Oxford English Dictionary © 2008 Oxford University Press:
Si

▶symbol the chemical element silicon.

Concise Oxford English Dictionary © 2008 Oxford University Press:
silicon /ˈsɪlɪk(ə)n/

▶noun the chemical element of atomic number 14, a shiny grey crystalline non-metal with semiconducting properties, used in making electronic circuits. (Symbol: Si)

– origin C19: alt. of earlier silicium, from L. silex, silic- ‘flint’, on the pattern of carbon and boron.