ha-ha

ha-ha. In landscape-gardening, a boundary to a garden designed not to interrupt a view from e.g. a country-house. It consists of a ditch with side or revetment nearest the viewpoint perpendicular (or slightly battered), faced with brick or stone, and the other side sloped and turfed. It kept animals away from the area contiguous to the house, yet was concealed. It appears to have been a French invention called ah, ah (said to be an exclamation of surprise, but more likely to be derived from a corruption of the Old English word for a hedge), described as having un fosse sec au pied in d'Argenville's La Théorie et la Pratique du Jardinage (1709), and may have been first used in England by Guillaume Beaumont (fl. late C17 and early C18) at Levens Hall, Westmor., around 1698. It was used in many English landscape gardens, notably by Bridgeman and Kent.

Bibliography

Goulty (1991);
Hadfield,, Harling,, & and Highton (1980);
Symes (1993)