The Collaborative International Dictionary of English v.0.48:

Yearly \Year"ly\, a. [AS. ge['a]rlic.]
   [1913 Webster]
   1. Happening, accruing, or coming every year; annual; as, a
      yearly income; a yearly feast.
      [1913 Webster]

   2. Lasting a year; as, a yearly plant.
      [1913 Webster]

   3. Accomplished in a year; as, the yearly circuit, or
      revolution, of the earth. --Shak.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Yearly \Year"ly\, adv. [AS. ge['a]rlice.]
   Annually; once a year to year; as, blessings yearly bestowed.
   [1913 Webster]

         Yearly will I do this rite.              --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

yearly
    adv 1: without missing a year; "they travel to China annually"
           [syn: annually, yearly, every year, each year]
    adj 1: occurring or payable every year; "an annual trip to
           Paris"; "yearly medical examinations"; "annual (or
           yearly) income" [syn: annual, yearly]
    n 1: a reference book that is published regularly once every
         year [syn: annual, yearly, yearbook]

Moby Thesaurus II by Grady Ward, 1.0:

36 Moby Thesaurus words for "yearly":
   annual, annually, biannual, biennial, bimonthly, biweekly,
   catamenial, centenary, centennial, daily, decennial, diurnal,
   fortnightly, hebdomadal, hourly, menstrual, momentary, momently,
   monthly, per annum, perennial, perennially, quarterly, quotidian,
   regular, regularly, secular, semestral, semiannual, semimonthly,
   semiweekly, semiyearly, tertian, triennial, weekly,
   year after year