The call-wires were usually equipped with drops in order that the exchange might be called at night when the operators were not listening continuously.
Hence the term is extended to signify the fall of such drops in a shower, and in the plural, "the rains," it signifies the rainy seasons in India and elsewhere where under normal climatic conditions such seasons are clearly distinguished from the dry.
Severe drops in oxygen levels lead to heart, lung and brain disorders, whilst chronic sleep deprivation causes extreme sleepiness during the day.
Tell her there are a few bitter drops in every one's cup, and the only way is to take the bitter patiently, and the sweet thankfully.
When version 2 of nearly any electronic equipment hits, the previous one immediately drops in price.