Ranked by relevance and common usage.
Keep "gillion" when the sentence already sounds natural, when a synonym would add unintended emphasis, or when readers need the most familiar wording. A synonym should clarify or sharpen the message, not simply make the sentence look more varied.
If two options seem close, choose the one that best matches the audience and purpose of the sentence.
Choose a synonym only if it keeps the core idea of "gillion" intact in the sentence you are editing.
Check whether the replacement sounds more formal, casual, emotional, technical, or forceful than the original word.
Read the full sentence after the swap. Keep the synonym only when the sentence becomes clearer or more precise.
Review note: Synonym lists are ranked with lexical data and reviewed for practical writing value. Use the comparison notes, sentence evidence, and source labels together; a high-ranking synonym can still be wrong when the audience, register, or grammar changes.
After choosing a replacement for "gillion", read the sentence once for meaning and once for rhythm. The best synonym should feel natural in the full sentence, not only accurate in a word list.
If the synonym makes the sentence slower, vaguer, or more dramatic than intended, keep "gillion" or choose a simpler alternative from the closest-match group.
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3 total sentences available.
The internationally agreed symbol for 10^6 is M and this is the initial letter of million. Would it not be logical and convenient to turn this happy accident into a principle and use G, the internationally agreed symbol for 10^9, as the initial letter of the word for 1,000,000,000? That number would thus be called a gillion. Whether the g should be hard or soft is a matter of opinion. I incline to hard because of the derivation from giga.
Source: wiktionary
At Guy's school there had been an outdoor pool, in use from April to October, a watery grave for a billion insects, or quite possibly a gillion or a squillion. The bright turquoise lining had wrinkled under the children's feet.
Source: wiktionary
I looked down to see my dog, Roof, short for Rufus, curled in sleep below the window, unworried by the wings of hummingbirds whirring at speeds of a gillion miles an hour as they flitted in and out of the trumpets of honeysuckle growing on the side of the house.
Source: wiktionary
Closest matches include enormous number, gazillion, large number, vast quantity, zillion.
Compare the replacement against real sentence context. This entry includes sample sentences so you can check tone, grammar, and meaning before swapping words.