Correct spelling, explanation: the word tomorrow comes from Old English to morrow meaning to morning. Words merged but their spelling remained, thus tommorrow is the wrong spelling.

Definition of tomorrow:
1. noun, the day after today
I don’t have to go to school tomorrow because it’s Saturday.
Shall we go to the cinema tomorrow? “Dirty Dancing” is being screened.
2. noun, sometime in the future
Let’s hope for a better tomorrow.
Who is hard-working today, is successful tomorrow.

Idioms and phrases with tomorrow:
→ tomorrow is another day, one shouldn’t focus on present failures because there will be new possibilities in the future:
Hey, don’t worry about not getting that job, tomorrow is another day!
She’s a huge optimist. She always says that it will get better because tomorrow is another day.

Incorrect spelling, explanation: the spelling tommorow is wrong because of the Old English origin from the correct spelling – tomorrow: to + morrow (meaning morning, the next day) so we need to double the r but not the m.

Incorrect spelling

Incorrect spelling

Incorrect spelling

Incorrect spelling