Most commonly, UK central government debt.
It may be dated (redeemable) or undated.
Undated gilts are perpetual debt, paying a fixed periodic coupon but having no final redemption date.
Gilt yields are conventionally quoted in the UK markets on a semi-annual basis.
Also known as Gilt-edged securities.
The term 'gilt' is also used to refer to the debt of certain other central governments, especially US government treasury securities.