Why is the ninth month called September?
1640s of whitening hair; 1680s of glass; 1734 of sugar or icing, past participle adjective from frost.
Old English forst, frost "a freezing, becoming frozen, extreme cold," from Proto-Germanic *frusta- (cf. Old Saxon, Old Frisian, Old High German frost, Middle Dutch and Dutch vorst), related to freosan "to freeze," from PIE *preus- "to freeze; burn" (see freeze (v.)). Both forms of the word were common in English till late 15c.; the triumph of frost may be due to its similarity to the forms in other Germanic languages.
A deposit of minute ice crystals formed when water vapor condenses at a temperature below freezing.
A deposit of tiny, white ice crystals on a surface. Frost forms through sublimation, when water vapor in the air condenses at a temperature below freezing. It gets its white color from tiny air bubbles trapped in the ice crystals. See more at dew point.
(Heb. kerah, from its smoothness) Job 37:10 (R.V., "ice"); Gen. 31:40; Jer. 36:30; rendered "ice" in Job 6:16, 38:29; and "crystal" in Ezek. 1:22. "At the present day frost is entirely unknown in the lower portions of the valley of the Jordan, but slight frosts are sometimes felt on the sea-coast and near Lebanon." Throughout Western Asia cold frosty nights are frequently succeeded by warm days. "Hoar frost" (Heb. kephor, so called from its covering the ground) is mentioned in Ex. 16:14; Job 38:29; Ps. 147:16. In Ps. 78:47 the word rendered "frost" (R.V. marg., "great hail-stones"), _hanamal_, occurs only there. It is rendered by Gesenius, the Hebrew lexicographer, "ant," and so also by others, but the usual interpretation derived from the ancient versions may be maintained.