I've always thought that (as stated in the Longman Dictionary):

annually = once every year

yearly = once each year

and that neither can really replace "every year" as both words are limited by the number of occurrence. For example, I would say "Dengue outbreaks occurs every year during the raining season" instead of "Dengue outbreaks occurs annually / yearly" simply because Dengue does not happen only once every year. However, Oxford Online Dictionary really confuses me as it also includes "every year" in the definition of these two words. Furthermore, it states:

Dengue fever occurs annually in Indonesia, with a peak occurring every five years.

Shall I trust Longman or Oxford?

  • Annually I find myself going around in circles.
    – Hot Licks
    Commented May 5, 2022 at 23:43
  • once every year = once each year
    – JsonKody
    Commented Apr 14, 2023 at 11:13

3 Answers 3


Either annually or yearly can and frequently does replace ‘every year’ as none of the phrases is limited by the number of occurrences, except to the extent that what happens twice a year is strictly biannual, not twice annually.

There is no difference at all among ‘annually’, ‘yearly’ or 'every year' and Longmans and Oxford Online don’t think there is. All their examples are almost wholly unhelpful but that doesn’t change any of their definitions.

Longman says annually means ‘once every year’ Longman’s example ‘The jazz festival is held annually in July’ is purely about grammar, not meaning. Test this by replacing it with ‘The jazz festival is held every 17 years in July’

Oxford says annually means ‘once a year; every year’ Oxford’s examples ‘the prize is awarded annually’ and ‘sales are increasing by about 17% annually’ purely about grammar, not meaning. Test this by replacing ‘annually’ with ‘every 17 days/weeks/months/years/centuries…’

Longman says yearly means ‘happening or appearing every year or once a year’ Oxford says yearly means ‘Happening or produced once a year or every year’

Your Dengue outbreaks seem very confusing. In my country your ‘rainy season’ does happen once a year; that's why it's called 'the rainy season'. We could be wrong and then so would you be, because more than one would necessarily be ‘seasons.’ If Dengue happens more than once a year then it happens several times or twice or however many times a year and certainly, that could and often would be expressed as ‘three times annually’ or ‘five times yearly’ or 'several times every year’ or '… each year' or '… in a year' or '… during the year'.

Usually more confusing are biannual, biennial and perennial none of which means the same either as each other or as annually/yearly/every year and about which again, Longman and Oxford agree. Their relevance here is to distinguish all of them from the examples in your question.

Longman’s biannual: happening twice each year Oxford’s biannual: Occurring twice a year

Longman’s biennial: a biennial event happens once every two years; a biennial plant stays alive for two years. Oxford’s biennial: Taking place every other year.

Longman’s perennial: continuing or existing for a long time, or happening again and again; a plant that is perennial lives for more than two years. Oxford perennial: Lasting or existing for a long or apparently infinite time; enduring or continually recurring


One key distinction between annually and yearly, is that the word annual is derived from latin according to Dictionary.com:

Late Latin annuālis, equivalent to Latin annu(us) yearly (derivative of annus circuit of the sun, year) + -ālis -al1; replacing Middle

Thereby, annual or annually despite being synonymous with yearly is considered to be more formal. For example:

Company X has just published its annual report.

It is very unlikely tho come across a yearly report.

Yearly is relatively informal, where it can be used:

Did you meet your yearly targets?

In short yearly can be either an adjective or an adverb. However annual is an adjective whereas annually is an adverb.


This is my first answer on the English StackExchange.

"Every" is used when referring to all the members of a group of three or more (it is more usual for a large number). We use "every" to generalize and it is always followed by a noun.

  • Every house in the town is painted white. (All of the houses were not painted uniquely)
  • Every girl in the class went to the party. ("Each girl went to the party" would sound awkward)
  • Every student deserves to receive the best education available in a safe and healthy environment. (all of the students, not just certain ones)

We use "each" in front of the singular form of a count noun to emphasize individuality. "Each" indicates two or more people or things (more usual for a small number). "Each" can be also an indefinite pronoun replacing a noun.

  • Each test contains about 15 questions.

  • Give each child some chocolate cake. (to each individual child)

  • You should make notes to help you remember each word separately. (one by one)

  • Each employee was given a bonus. (to each individual employee)

As I see it, yearly is meant for a specific set of time periods, while annually is used for longer periods of time. When you are talking about the yearly bake sale, you would mean the bake sale happening each year. When you are talking about the annual bake sale, you mean every upcoming bake sale.

  • Each year, we raise funds by having bake sales.
  • We have bake sales every year.

If you think about how each year and every year affect the sentences, you will see how the sentences have different meaning.

I would trust the Longman dictionary on this.

  • Many thanks for your detailed explanation. It really helps a lot!
    – selche
    Commented Jan 31, 2017 at 23:46
  • Please include links to the website(s) that you are quoting. Commented May 13, 2018 at 6:10

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