Redresser vs. lisser
While both redresser and lisser can translate to "to straighten" in English, they address different physical actions. Redresser focuses on structure and direction, specifically correcting something that is bent or crooked. In contrast, lisser focuses on texture and surface, meaning to smooth something out.
Redresser
B2This verb is used when something needs to be unbent, untwisted, or returned to an upright position. It implies correcting a shape or a trajectory that has gone wrong. Figuratively, redresser is also used to describe fixing a bad situation or correcting a wrong.
Le mécanicien a réussi à redresser le pare-chocs tordu après l'accident.
(The mechanic managed to straighten the bent bumper after the accident.)
Si tu veux soulager ton dos, tu dois te redresser quand tu es assis.
(If you want to relieve your back, you must straighten up when you are seated.)
Le capitaine a dû redresser la barre pour éviter les rochers.
(The captain had to straight the helm to avoid the rocks.)
Les nouvelles mesures devraient redresser l'économie du pays.
(The new measures should straighten out the country's economy.)
Il a essayé de redresser le cadre qui penchait sur le mur.
(He tried to straighten the frame that was tilting on the wall.)
Lisser
B2This verb means to make something smooth, flat, and free of wrinkles, bumps, or frizz. It relates to the texture of a surface. This is the correct word to use when talking about straightening curly hair or smoothing out a material like cement, cream, or fabric.
Elle passe une heure dans la salle de bain pour lisser ses cheveux.
(She spends an hour in the bathroom to straighten her hair.)
Utilise une spatule pour lisser le glaçage sur le gâteau d'anniversaire.
(Use a spatula to smooth the frosting on the birthday cake.)
Le maçon doit lisser le béton avant qu'il ne sèche complètement.
(The mason must smooth the concrete before it dries completely.)
Elle a lissé le pli de sa jupe avec la paume de la main.
(She smoothed the crease in her skirt with the palm of her hand.)
L'entreprise veut lisser ses dépenses sur l'année entière.
(The company wants to smooth (even out) its expenses over the entire year.)
Summary
Use redresser when correcting a bend, a curve, or a lean to make an object straight or upright again (like a bent nail or bad posture). Use lisser when removing texture, curls, or wrinkles to make a surface flat and smooth (like hair, icing, or fabric).