Tromper
Il n’y a pas à s’y tromper = There is no mistake about it.
Trop
Je ne sais trop = I don’t exactly know.
*Qui dit trop ne dit rien = He who wants to prove too much proves nothing.
Trou
Faire un trou à la lune (fam.) = To shoot the moon; To fly from one’s creditors.
Troubler
C’est un trouble-fête = He is a mar-joy, a wet blanket.