Something that fills up, completes, or supplements something else; a fulfillment.
From Latin expletum (filled out), past participle of explere (to fill out). The -ment suffix creates a noun form, similar to accomplishment or fulfillment.
Explement is an archaic word that linguists love because it shows how -ment transforms verbs into nouns—the word itself is nearly extinct, but it perfectly illustrates English word-building patterns.
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