The common abbreviation for the word “appointment” is “appt.” Though it's not the most common of abbreviations it's nonetheless a widely agreed upon one. Special attention should be paid to the spelling as “apt.” is a completely different abbreviation, in this case for the word apartment.

What is appt short for?

Definition. APPT. Appointment. APPT. Activated Partial Thromboplastin Time (clotting measure)

What does it mean for something to be apt?

1 : unusually fitted or qualified : ready proved an apt tool in the hands of the conspirators. 2a : having a tendency : likely plants apt to suffer from drought. b : ordinarily disposed : inclined apt to accept what is plausible as true. 3 : suited to a purpose especially : being to the point an apt quotation.