Completion and Day one

Completion

Completion noun - A concluding action.

Day one is an antonym for completion.

Day one

Day one noun - The point at which something begins.
Usage example: since day one of this project, we've always insisted that we would create the best product possible without any consideration of cost

Completion is an antonym for day one in topics: beginning, start of an event or action.
Cite this Source
Day one and Completion. (2016). Retrieved 2026, August 15, from https://thesaurus.plus/related/completion/day_one
Completion & Day one. N.p., 2016. Web. 15 Aug. 2026. <https://thesaurus.plus/related/completion/day_one>.
Day one or Completion. 2016. Accessed August 15, 2026. https://thesaurus.plus/related/completion/day_one.
Google Ngram Viewer shows how "completion" and "day one" have occurred on timeline