An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

1) Meteo.: Any form of water, such as rain, snow, sleet, or hail, that falls to the Earth's surface. The quantity of such water falling in a specific area within a specific period.
2) Chemistry: The process of separating a solid substance from a solution.

From M.Fr. précipitation, from L. præcipitationem "act or fact of falling headlong, haste," from præcipitare "fall, be hasty," from præceps "steep, headlong, headfirst," from præ- "forth" + caput, → head.

1) Bâreš, verbal noun of bâridan "to rain," bârân "rain;" Mid.Pers. vâritan, vârân; Av. vār- "rain; to rain;" cf. Skt. vār- "rain, water; to rain;" PIE base *uer- "water, rain, river."
Rizeš, verbal noun of rixtan "to flow, to pour," → overflow.
2) Tahnešast "to settle down, precipitate," from tah "→ bottom, end;" + nešast past stem of nešastan "to sit down; to settle down; to sink," → sit.