plural frosts
1
: a thin layer of ice that forms on the ground, on grass, etc., when the air becomes cold
The grass was covered with frost.
light/heavy frost
Frost formed on the window.
2
: the occurrence of weather that is cold enough to cause water to freeze and frost to form
These plants should bloom until the first frost of the season.
We had an early/late frost.
a killing frost [=weather that is so cold that the frost kills plants]
frosts; frosted; frosting
1
a
: to cover (something) with frost
The cold had frosted the windows.
b
: to become covered with frost
The windows frosted (up).
2
chiefly US
: to cover (something, such as a cake) with frosting (sense 1)
I have to frost the birthday cake.
3
chiefly US
: to make small strips of your hair lighter so the top layer of your hair is lighter than the rest of it
She frosts her bangs.
Cite this Entry
“Frost.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/frost. Accessed 22 Jun. 2026.
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