installment

Etymology 1

A 1732 alteration of estallment, from Anglo-Norman estaler (“fix payments”), from Old French estal (“fixed position”), from Old High German stal (“stall", "standing place”) : The sense of "part of a whole produced in advance of the rest" is from 1823.

noun

1. One of a series of parts, whether equal or unequal to the other parts of the series, of a given entity or a given process, which part presents or is presented at a particular scheduled interval.
   Granted, this was but the first installment in the long process of “hatching” and mastering a dragon egg, but it was a good start. 2009, Richard Leviton, Santa Fe Light: Touring the Visionary Geography of Santa Fe, New Mexico
   The blessings of the kingdom (healing, freedom, Stan's defat, abundant life, relationship with the King) are available now. Yet they are available only as a foretaste, the first installment of what will come when Christ returns. 2014, Karen Lee-Thorp, A Compact Guide to the Christian Life
   Now bands like Mumford and the Lumineers are fulfilling that role, but they're also becoming the latest installment of the whole "indie goes mainstream"/"mainstream co-opt indie" thing that's been happening since Seth Cohen's heyday -- or, you know, since Don Draper married Megan. 2015, How to Write About Music, page 193
2. (banking, finance) One member of a series of portions of a debt or sum of money, which portions may or may not be equated (depending in part on whether the interest rate is fixed or variable), payment of which portions are serially exacted at regularly scheduled intervals toward satisfaction of the total. Payments of installments are generally mensual, quarterly, triannual, biannual, or annual.
3. (publishing, media) A part of a published or broadcast serial.
   With The Two Towers, the new installment of the Lord of the Rings trilogy, about to storm the box office, we are seeing what might be called the enchanting of America. 2010, Michael A. Cramer, Medieval Fantasy as Performance, page ix
   It is a serial story which we are all reading, and which grows in vital interest with each successive installment. 2012, Charles W. Chesnutt, The Marrow of Tradition

Etymology 2

From install + -ment, install from Old French installer, from Medieval Latin installare, from Medieval Latin in- and Medieval Latin stallum, stall from a Germanic source (compare Old High German stal).

noun

1. The act of installing; installation.
   In the twenty-two years Faellon had been Chief Servant, he had officiated at many royal ceremonies, including the burial of Joakal's father and mother, and Joakal's own installment as King nine years ago. 2000, Rebecca Neason, Guises of the Mind, page 183
2. (obsolete) The seat in which one is placed.