Completion (noun)

1. The act of finishing something.
2. The state of being finished.
3. Something that finishes or completes something else.

Origin:

Derived from the latin word 'complere' meaning 'to fill up'.

Examples:

1. The completion of the bridge marked a major milestone for the city.
2. She felt a sense of accomplishment upon the completion of her thesis.
3. The final touch of a painting is its completion.