dropping (n.)

Middle English droppen, from Old English dropian "to fall in drops, fall in small portions or globules, as a liquid." The word is part of a related series of verbs in Proto-Germanic that also yielded Old Saxon driopan, Old Frisian driapa, Dutch druipen, Old High German triufan, German triefen, and in English drip, droop, and obsolete dreep and dripe. Related: Dropped; dropping.

In reference to a solid object, "to fall vertically" from late 14c. The transitive sense "allow to fall" is from mid-14c. To drop in "visit casually" is from c. 1600; drop-in (n.) "a casual visit" is attested by 1819. The notion in drop (someone) a line "write a letter" (1769) is of dropping a message into a letter-box. Exclamation drop dead to express emphatic dislike or scorn is from 1934; as an adjective meaning "stunning, excellent" it is recorded by 1970 (compare killing, etc.).