A publication that's published every two months is a bi-monthly. That would be six issues per year. There was some abiguity in the past with the term sometimes being used to mean both twice a month and every two months. There was a gradual shift in the late twentieth century to that term being used to indicate every two months.
A term for something that occurs every eighteen months is "biennial." However, more specifically, to denote an interval of eighteen months, you might use the term "semiannual" to imply a frequency of twice a year, though it does not precisely match the eighteen-month interval. Another option is "18-month cycle."
Quarterly.Quarterly.Quarterly.Quarterly.
The term used is 'triannual'. It should not be confused with triennial, which means the journal is published only once in every three years.
it is a a centry
tercentennial
A short term investment could be something that you would use in the next couple months or years, such as a Certificate of Deposit. A long term investment would be something that you may not be using until your retirement.
scientific law
The term for every three months is "quarterly." This period is commonly used in business and finance to denote events, reports, or payments that occur four times a year. Each quarter represents one-fourth of a year, typically labeled as Q1, Q2, Q3, and Q4.
scientific law
bimonthly can be used to mean this. Since bimonthly can also refer to "twice a month",it needs to be used with caution.
Every six months is referred to as "semiannual" or "biannual." In certain contexts, it may also be described as "semiannually." This term is commonly used in finance, education, and various reporting scenarios to indicate events or activities that occur twice a year.
"Fortnight" is a term that means a period of two weeks. So, "every fortnight" means something that occurs or happens once every two weeks.