initial
US /ɪˈnɪʃ.əl/
UK /ɪˈnɪʃ.əl/

1.
initiale
the first letter of a name or word, typically a person's first name or a significant word in a phrase.
:
•
Please write your initials at the bottom of the form.
Veuillez écrire vos initiales en bas du formulaire.
•
Her necklace had her boyfriend's initial on it.
Son collier portait l’initiale de son petit ami.
1.
parapher
mark (a document) with one's initials, typically as a sign of approval or to indicate that one has read it.
:
•
Please initial each page of the contract.
Veuillez parapher chaque page du contrat.
•
She initialed the changes to confirm her approval.
Elle a paraphé les modifications pour confirmer son approbation.