per year, or annually; used in expressing the interest rate, which is usually calculated as a percentage for a period of one year (e.g. 4.5% p.a.). If this figure is missing from the interest rate, it must be ascertained whether this is an oversight and the interest rate will be applied annually or in relation to another period, e.g. per month (per mensem, p.m.), per week (per septimanam, p.sept.) or per day (per diem, p.d.).