/ ˈmægnɪtjuːd; NAmE -tuːd/ noun magnitude (of sth)
1.
[ U ] ( formal ) the great size or importance of sth; the degree to which sth is large or important :
We did not realize the magnitude of the problem.
a discovery of the first magnitude
2.
[ C , U ] ( astronomy ) the degree to which a star is bright :
The star varies in brightness by about three magnitudes.
3.
[ C , U ] ( geology ) the size of an earthquake
••
WORD ORIGIN
late Middle English (also in the sense greatness of character ): from Latin magnitudo , from magnus great.