It is interesting when learning a language how one day you have never heard a word and then you suddenly hear it all the time.
That is what happened with the word déclancher. I had never heard it until our landlord used it when explaining how to test the boiler.

Then I went to a union meeting at work and it was déclancher this déclancher that.
It means to start. It was a similar story with the word basculer when I first arrived. Never heard it but very quickly there was basculer and bascule par tout. It means to toggle, topple, tip.
Other words I heard for the first time this week – gaspillage (waste) and pilotage (manage).