Semi-annual rate
From ACT Wiki
The semi-annual rate is the simple annual interest quotation for compounding twice a year.
For example if the semi-annual rate is quoted as 10%, then the periodic interest accruing is 5% (= 10% x 6/12) per six month period.
A semi-annual rate is an example of a nominal annual rate.
The semi-annual rate is not to be confused with the periodic rate per 6 months, which in this case is 5%.
Nor should it be confused with the related annual effective rate, which in this case would be = 1.052 - 1 = 10.25%.