-ment

turns a verb into a noun naming the action, result, or means

Spelled -ment · -mentum 'result, means, or instrument of an action'

Latin -mentum named a result or means: achievement marks achieving, adjustment follows adjusting, and an instrument serves a task.

Words built from it

achievement — something successfully accomplished
achieve + -ment (act or result)
adjustment — a change made to improve a fit or situation
adjust + -ment (act or result)
government — the system or group that governs
govern + -ment (action or system)
nourishment — food or support that promotes growth
nourish + -ment (act or result)
instrument — a tool used to perform a task
instru- (equip or build) + -ment (means)
monument — a structure that preserves a memory
mon- (remind) + -ment (means or result)

element — It comes from Latin elementum, whose final letters are not the suffix -ment.

-ize — turns a noun or adjective into a verb meaning make, become, or treat in that way
-less — turns a noun into an adjective meaning without or lacking it
-ness — turns an adjective into a noun naming its state, condition, or quality
-ology — turns a subject into the name of its study or body of knowledge
-ous — turns a noun or root into an adjective meaning full of, having, or characterized by it