IPA: /ˈfɔːtnaɪt/
KK: /ˈfɔrtˌnaɪt/
A time span of two weeks or 14 days.
We will meet again in a fortnight to discuss the project.
Fortnight is derived from the Old English "feowertyne niht" (meaning fourteen nights). The term combines "feower" (meaning four) and "tīene" (meaning ten), indicating a period of two weeks or fourteen nights.
Think of 'fourteen nights' to remember that a fortnight is a period of two weeks.