\Su"per*tax`\, n. [Super- + tax.]
A tax in addition to the usual or normal tax; specif., in the
United Kingdom, an income tax of sixpence for every pound in
addition to the normal income tax of one shilling and
twopence for every pound, imposed, by the Finance Act of
1909-1910 (c. 8, ss 66, 72), on the amount by which the
income of any person exceeds [pounds]3,000 when his total
income exceeds [pounds]5,000.