1) Bit of drizzle 2) Bit of precipitation 3) Driblet 4) Drizzle unit 5) Drop 6) Exclusively Anglo word 7) Exclusively Saxon word 8) Hail origin 9) Kerplop maker 10) Nimbostratus output 11) One coming down 12) Precipitation indication 13) Shower harbinger 14) Shower unit 15) Something from heaven 16) Start of a deluge 
• (n.) A drop of rain.
(from the article `climate`) Growing clouds are sustained by upward air currents, which may vary in strength from a few centimetres per second to several metres per second. ... Liquid waterdrops with diameters greater than those of drizzle constitute rain. Raindrops rarely exceed 6 mm (0.2 inch) in diameter because they ... Concentra...
Rain'drop` (-drŏp`) noun A drop of rain. 
[n] - a drop of rain
noun a drop of rain