At once
At once adverb - Without delay or hesitation; with no time intervening.
On one occasion and at once are semantically related. In some cases you can use "On one occasion" instead an adverb phrase "At once".
On one occasion
At once and on one occasion are semantically related. Sometimes you can use "At once" instead an adverb phrase "On one occasion".
Mutual synonyms
Both terms in one sentence
- The third boss, purple Arachnoid, reappears throughout the last two stages - on one occasion, six of them at once.
Source: Degraded Boss -
On one occasion he even used all four at once when sufficiently pissed off (He is the only person in history to have mastered the sword-chucks, let alone dual-wielding them).
Source: Dual Wielding - She doesn't so much heal injuries as temporarily take them away, and once her Innocence is deactivated they all come flooding back at once (which has, on one occasion, led to characters taking fatal injuries and fighting on, only to have to face their death at the end of the fight anyway.)
Source: Harmful Healing
Cite this Source
On one occasion and At once. (2016). Retrieved 2026, August 03, from https://thesaurus.plus/related/at_once/on_one_occasion
At once & On one occasion. N.p., 2016. Web. 03 Aug. 2026. <https://thesaurus.plus/related/at_once/on_one_occasion>.
On one occasion or At once. 2016. Accessed August 03, 2026. https://thesaurus.plus/related/at_once/on_one_occasion.
