There are 2 translations of tranquilo in English:

tranquilo1

(-la)

adjetivo/adjective

  • 1.1[estar] (libre de preocupaciones) ahora que consiguió empleo estoy más tranquilo I feel better o/or happier now that he's found a job viven tranquilos allí en su granjita they lead a peaceful o/or tranquil life on their little farm ¡tranquilo! relax! o keep calm! o don't worry! tú, tranquila, que de eso me encargo yo there's no need for you to worry o/or don't worry, I'll take care of that no estaré tranquila hasta que llame I won't relax until he calls no estará tranquilo hasta que lo rompa he won't be happy o/or satisfied until he breaks it! déjalo tranquilo leave him alone tengo la conciencia tranquila I have a clear conscience, my conscience is clear 1.2[ser] [persona] (pacífico) calm 1.3[estar] [mar/ambiente] calm; [lugar] quiet, peaceful, tranquil llevan una vida muy tranquila they lead a very quiet life 1.4[estar] (sin inmutarse) su hermano está en el hospital y él tan tranquilo his brother's in hospital and he doesn't seem at all worried o bothered o perturbed me dijo que se lo había llevado ella y se quedó tan tranquila she told me she had taken it, as cool as you like o as cool as a cucumber o quite unashamedly, she told me, quite calmly o/or boldly, that she had taken it el tren pasó casi rozando y ellos se quedaron tan tranquilos the train passed within an inch of us and they didn't turn a hair o/or they didn't bat an eyelash (inglés norteamericano/American English) o/or (inglés británico/British English) eyelid, the train passed within an inch of us and they were quite unperturbed lo dijo mal y se quedó tan tranquilo he said it wrong but he just carried on regardless o/or as if nothing had happened, he said it wrong but he was completely unfazed o/or unabashed