Of the current month. In commercial English it used to be common to refer to a date as, for example, the 5th instant, or more usually 5th inst., meaning the 5th of the current month. Ultimo refers to the previous month; for example, the 5th ultimo, or more usually the 5th ult., means the 5th of last month. Proximo refers to the next month; the 5th proximo, or 5th prox., means the 5th of next month.
Subjects: Business and Management.