Noun si has 3 senses
  1. Systeme International d'Unites, Systeme International, SI system, SI, International System of Units, International System - a complete metric system of units of measurement for scientists; fundamental quantities are length (meter) and mass (kilogram) and time (second) and electric current (ampere) and temperature (kelvin) and amount of matter (mole) and luminous intensity (candela); "Today the United States is the only country in the world not totally committed to the Systeme International d'Unites"
    --1 is a kind of metric system
  2. silicon, Si, atomic number 14 - a tetravalent nonmetallic element; next to oxygen it is the most abundant element in the earth's crust; occurs in clay and feldspar and granite and quartz and sand; used as a semiconductor in transistors
    --2 is a kind of chemical element, element; semiconductor, semiconducting material
    --2 is a substance of
     silicone, silicone polymer; clay; feldspar, felspar; granite; quartz; sand
  3. ti, te, si - the syllable naming the seventh (subtonic) note of any musical scale in solmization
    --3 is a kind of solfa syllable
,
TOP