trompait

/tʁɔ̃.pɛ/tromper
1.
verbInd1stImparfaitSing3

was cheating on (a partner)

was deceiving / was misleading (someone)

Il trompait sa compagne depuis six mois avant qu'elle ne s'en aperçoive.

He had been cheating on his partner for six months before she noticed.

Synonyms:avait une liaison, avait une aventure, duper, induire en erreur, mentir (à)
2.
verbInd1stImparfaitSing3

was mistaken

was wrong

Je pensais qu'il avait raison, mais il se trompait complètement.

I thought he was right, but he was completely wrong.

Synonyms:se méprenait, avait tort, se plantait