Term
Third Shot Drop
Also called: 3rd Shot Drop, Drop Shot
A soft shot the serving side hits as the third shot, dropping it into the opponent's kitchen.
A shot where the serving side drops the third shot softly into the opponent's non-volley zone (kitchen) (Pickleball.com). Because of the Two-Bounce Rule, the third shot must bounce before you hit it (10.A, 10.A.2). Hitting a drop is said to give you time to move up to the net (USA Pickleball).
USA Pickleball calls the third shot one of the most important and most difficult shots (USA Pickleball).
See it in a figure
This figure is from the rule "Two-Bounce Rule".
How to read the sources: numbers like (8.F.4) are rulebook sections, and links are outside sources. An "Author's note" is the author's personal experience, not an official rule.