A sundae is an ice cream dessert piled with toppings like syrup or nuts, while Sunday is the day of the week that comes after Saturday. They're pronounced the same, so the only way to keep them straight is the spelling: -dae for dessert, -day for the day.
The core difference
Sundae is a dessert; Sunday is a day of the week.
- sundae — ice cream topped with things like syrup, fruit, or nuts: We ordered a chocolate fudge sundae after dinner.
- Sunday — the day of the week after Saturday: We always have a big family lunch on Sunday.
How to tell them apart
Because the two words sound identical, spelling is the only real clue in writing. A handy trick is that sundae ends the way a dessert menu might spell things — with an unusual "-ae" — while Sunday keeps the ordinary "-day" ending shared by every other day of the week.
It's thought that "sundae" began as a playful respelling of "Sunday," possibly tied to selling ice cream treats on that day, which is exactly why the two remain so easy to mix up in casual writing. Remembering that Sunday is always capitalised, while sundae never is, is another quick check when proofreading a menu or a diary entry.
