Definite frequency adverb

From Teflpedia

A definite frequency adverb is an adverb used to express definite frequency.

There are a few of these in English; they are typically made by adding the suffix -ly to time nouns.

These may form the head of an adverb phrases such as "twice-hourly", or "four times weekly" which would be definite frequency adverb phrases.

It’s possible to work out additional entries in this list using Latin numbers.

Be careful with "biannual" as it’s ambiguous (do you mean twice a year or once every two years?)

Time period adverb
hour hourly
day daily
week weekly
fortnight fortnightly
month monthly
half-year half-yearly, semiannually
year annually, yearly
2 years biennial
3 years triennial
4 years quadrennially
5 years quinquennially
10 years decennially
20 years duodecennially
50 years semicentennial
100 years centennially
1000 years millennially