cautionner

Meaning (in English)

Cautionner means to act as a guarantor / surety for someone, i.e. to guarantee another person’s obligation or debt. In practice, it often refers to signing as a “caution” (a guarantor) for a lease, a loan, or any commitment where you promise to pay or fulfill the obligation if the main person does not.

In some contexts, it can also mean to secure something by a guarantee or deposit, depending on usage.

Parts / structure

• Built on the noun caution:
  • caution = guarantee, surety (and also deposit / security deposit depending on context)
  • -ner = a common verb-forming ending meaning “to make/do/provide”
• So cautionner ≈ “to provide a guarantee / to stand surety”

French synonyms

• se porter caution (pour quelqu’un) (very common and often the clearest equivalent)
• garantir (to guarantee)
• se rendre garant (de / pour) (to make oneself the guarantor)
• assurer (to assure/guarantee, depending on context)

French antonyms (where applicable)

• refuser de se porter caution (to refuse to stand surety)
• dégager / libérer (quelqu’un) de son cautionnement (to release someone from their guarantee)
  (Not a strict single-word antonym, but an opposite action in legal/financial contexts.)