si

• POS: Noun

CIDE DICTIONARY

si,  [It.].

 A syllable applied, in solmization, to the note B; more recently, to the seventh tone of any major diatonic scale. It was added to Guido's scale by Le Maire about the end of the 17th century.  [1913 Webster]

OXFORD DICTIONARY

si, abbr.
1 (Order of the) Star of India.
2 the international system of units of measurement (F Syst{egrave}me International).

si, symb. Chem. the element silicon.

si, n. Mus. = TE.

Etymology

F f. It., perh. f. the initials of Sancte Iohannes: see GAMUT