Meaning

noun a hard grey lustrous metallic element that is highly resistant to corrosion; occurs in niobite and fergusonite and tantalite

originAltered from si in the 19th century to prevent having two notes of the musical scale starting with the same letter, to become ti. vowel changed to 'a' to signify a flattened note.

Etymology from Wiktionary, CC BY-SA 3.0