A stream of even (equal) cash flows occurring at regular intervals- such as even monthly lease payments. An annuity in advance is one in which the annuity payment is due at the beginning of each period. An annuity in arrears is one in which the annuity payment is due at the end of each period.
ANNUITY
Meaning of ANNUITY in English
Finance-Leasing English vocabulary. Английский словарь финансов и лизинга. 2012