This is the 15411th most frequent German word.
verlangsamte
"Slowed down"
Here, "verlangsamte" is a verb in its simple past form meaning "slowed down." It is used to describe the action of reducing speed in the past.
Der Zug verlangsamte seine Geschwindigkeit vor dem Bahnhof.
The train slowed down its speed before the station.
In this example, "verlangsamte" refers to the act of intentionally reducing the pace of speaking.
Der Professor verlangsamte seine Rede, damit alle folgen konnten.
The professor slowed down his speech to ensure that everyone could follow.
Here, "verlangsamte" is used reflexively to depict the situation of the traffic gradually becoming slower.