The Gàidhealtachd ([kɛːəl̪ˠt̪əxk] listen , English: Gaeldom), sometimes known as A' Ghàidhealtachd (English: The Gaeldom), usually refers to the Highlands and Islands of Scotland and especially the Scottish Gaelic-speaking culture of the area. The corresponding Irish word Gaeltacht refers strictly to Irish-speaking areas.
The term is also used to apply to the Scottish Gaelic-speaking Canadian areas of Nova Scotia and Glengarry County, Ontario.
"The Gàidhealtachd" is not truly interchangeable with "Scottish Highlands" as it refers to the language and not to the geography. Also, many parts of the highlands no longer have substantial Gaelic-speaking populations, and some parts of what is now thought of as the Highlands have long been Scots-speaking or English-speaking areas: Caithness, Cromarty, Grantown-on-Spey, Campbeltown, etc. Conversely, several Gaelic-speaking communities lie outwith the Highland, Argyll and Bute and Outer Hebrides council areas, for example Isle of Arran and parts of Perth and Kinross. Gàidhealtachd also increasingly refers to any region where Scottish Gaelic is spoken as a first language by much of the population.