Anniversary means “a day for important events”, and the origin is derived from annus (year) and vertere (turn). The original idea is Latin anniversarius (come back every year). Synonym is memorial day. Let’s see an example sentence.
A close couple celebrates a wedding anniversary every year. Especially in America, the 25th anniversary of marriage is called silver anniversary. 50th anniversary of marriage is called golden anniversary. A child who loves their parents visits a grave at their death anniversary. The founding anniversary of the school is a holiday for the students. August 15th is the Japanese war-end anniversary.
Annual means “relating to one year”, and the etymology comes from annus (year). Annual means the event happens once a year. Synonym is yearly. Let’s see an example sentence.
School excursion, sports festival, cultural festival, and graduation ceremony are annual events of the school. Junior high school students and high school students receive annual exams at the end of the year. Company officers participate in the annual conference and prepare an annual report.
Annual also means that activities have been going on for a year. Let’s see an example sentence.
The annual income is an indicator to measure the individual’s economic strength. The annual growth rate of the Japanese economy in 2017 is about 1%. Japan’s capital investment law prohibits lending money with an annual interest rate of 29.2% or more. The number of credit cards free of annual membership expenses is increasing recently. The average annual rainfall in Japan is about 1,700 mm.
Annuity means “money received every year”, and the origin is derived from annus (year). Synonym is pension.
Annuity is a type of financial product. By paying insurance fee while working, you can receive money every year after retirement. Annuity mainly refers to private pension, and individuals can subscribe voluntarily. Annuity is also used for the annual payment of high prize winning lotteries.
The word “pension” mainly refers to the public pension, and the country or company forced individuals to join it. We Japanese have to pay national pension or welfare pension.
millenniumは「1000年間」を意味し、語源はmille（1000）とannus（年）に由来します。同義語はone thousand yearsです。
Millennium means “1000 years”, and the etymology comes from mille (1000) and annus (year). Synonym is one thousand years. Let’s see an example sentence.
The year 2000 is the beginning of the new millennium. The Millennium Bug or the Year 2000 problem is the problem that the computer malfunctions in 2000. It is feared that the computer would mistake the 2000 year as 1900, but it was just a needless worries.
Perennial means “long-term”, and the etymology comes from per (through) and annus (year). Synonyms are constant, continual. Let’s see an example sentence.
Declining birthrate and population aging has been perennial problems in Japan. Economic disparity is a perennial problem of the capitalist state. A perennial effort is necessary to succeed in blog business.
Perennial is also used in botany. Perennial plants are plants with a lifespan longer than 2 years. Trees are classified as perennial plants.