We don't have synonyms for ground frost yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are ground rose and ground frosts.
(n) :
(meteorology) The condition of air temperature dropping below the freezing point at or near ground level.
(n) :
Ice produced by the direct deposition of water vapor on grass, trees and other objects in freezing conditions.
(n) :
The frozen upper level of soil, caused by the air temperature dropping below the freezing point for a lengthy period of time; in temperate climates the soil thaws completely for the summer and in cold climates it may develop to permafrost.
(n) :
(meteorology) The condition of air temperature dropping below the freezing point at or near ground level.
(n) :
Ice produced by the direct deposition of water vapor on grass, trees and other objects in freezing conditions.
(n) :
The frozen upper level of soil, caused by the air temperature dropping below the freezing point for a lengthy period of time; in temperate climates the soil thaws completely for the summer and in cold climates it may develop to permafrost.