Your regular monthly mortgage payment.
Merriam-Webster Online Dictionary
installment (noun) - installation
1.
one of the parts into which a debt is divided when payment is made at intervals
2.
a) one of several parts (as of a publication) presented at intervals
b) one part of a serial story
Merriam-Webster Online Thesaurus
installment (noun)the process or an instance of being formally placed in an office or organization
SYNONYMS:
baptism, inaugural, inauguration, induction, initiation, installment ( instalment), investiture, investmentRELATED WORDS:
enlistment, enrollment ( enrolment); promotionNEAR ANTONYMS:
discharge, removal