from The American Heritage® Dictionary of the English Language, 4th Edition
- adv. By the year; annually: a magazine subscription of 40 dollars per annum.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- adv. annually
- adv. in, or for each year
from the GNU version of the Collaborative International Dictionary of English
- prep. by the year; in each successive year; annually.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- adv. by the year; every year (usually with reference to a sum of money paid or received)
Latin : per, per + annum, accusative of annus, year.(American Heritage® Dictionary of the English Language, Fourth Edition)
From post-classical Latin per annum, English from the 16th century. (Wiktionary)