To formally tell someone about something, especially in writing.
“We are writing to notify you that your application has been approved.”
“Please notify our office at least 48 hours before cancelling your appointment.”
Watch for the pattern 'We are writing to notify you that...' near the start of a letter, since it usually states the letter's main purpose directly. This makes it a strong clue for 'why was this letter written' questions in Reading Part 1.
Synonyms: inform, advise, alert