For past tense:
* "utilisé" (masculine singular) - used (e.g., "J'ai utilisé un stylo rouge." - I used a red pen)
* "utilisée" (feminine singular) - used (e.g., "Elle a utilisé une cuillère." - She used a spoon)
* "utilisés" (masculine plural) - used (e.g., "Ils ont utilisés des crayons." - They used pencils)
* "utilisées" (feminine plural) - used (e.g., "Elles ont utilisées des gommes." - They used erasers)
For "used to" (meaning a past habit):
* "avait l'habitude de" (formal) - used to (e.g., "Elle avait l'habitude de lire avant de dormir." - She used to read before going to sleep.)
* "avait pour habitude de" (formal) - used to (e.g., "Il avait pour habitude de manger des frites." - He used to eat fries.)
* "avait l'habitude" (informal) - used to (e.g., "J'avais l'habitude de jouer au football." - I used to play football.)
* "faisait" (informal) - used to (e.g., "Il faisait du vélo tous les jours." - He used to ride his bike every day.)
For "used" in the sense of "being employed":
* "employé" (masculine singular) - used (e.g., "Le logiciel est employé pour analyser les données." - The software is used to analyze data.)
* "employée" (feminine singular) - used (e.g., "La machine est employée pour produire des voitures." - The machine is used to produce cars.)
For "used" in the sense of "worn out":
* "usé" (masculine singular) - used (e.g., "Le tapis est usé." - The carpet is worn out.)
* "usée" (feminine singular) - used (e.g., "La robe est usée." - The dress is worn out.)
* "usés" (masculine plural) - used (e.g., "Les pneus sont usés." - The tires are worn out.)
* "usées" (feminine plural) - used (e.g., "Les chaussures sont usées." - The shoes are worn out.)
Make sure you use the correct form of "used" based on the context and gender of the noun it modifies.