Once
Once adjective - Having been such at some previous time.
Second and once are semantically related. in as soon as topic. In some cases you can use "Second" instead a conjunction "Once".
Second
Second noun - A very small space of time.
Once and second are semantically related. Sometimes you can use "Once" instead a conjunction "Second".
Cite this Source
Second and Once. (2016). Retrieved 2026, July 21, from https://thesaurus.plus/related/once/second
Once & Second. N.p., 2016. Web. 21 Jul. 2026. <https://thesaurus.plus/related/once/second>.
Second or Once. 2016. Accessed July 21, 2026. https://thesaurus.plus/related/once/second.
Google Ngram Viewer shows how "once" and "second" have occurred on timeline