Definition of si in English:

si

noun

Music
  • another term for te

Origin

Early 18th century: from the initial letters of Sancte Iohannes, the closing words of a Latin hymn (see solmization).

Pronunciation:

si

/siː/

Definition of SI in English:

SI

  • 1The international system of units of measurement.

  • 2Law
    Statutory instrument.

Pronunciation:

SI

/ɛsˈʌɪ/

Definition of Si in English:

Si

  • The chemical element silicon.